Accident & Emergency
Radiology
A Survival Guide
THIRD EDITION
Nigel Raby, MB ChB, MRCP, FRCR
Consultant Radiologist, Western Infi rmary, Glasgow
Laurence Berman, MB BS, FRCP, FRCR
Lecturer and Honorary Consultant Radiologist, University
of Cambridge and Addenbrooke's Hospital, Cambridge
Simon Morley, MA, BM BCh, MRCP, FRCR
Consultant Radiologist, University College Hospitals,
London Gerald de Lacey, MA, MB BChir, FRCR
Consultant to Radiology Red Dot Courses, London,
(www.radiology-courses.com)
Edinburgh • London • New York • Oxford • Philadelphia •
St Louis • Sydney • Toronto 2015
Table of Contents
Cover image
Title page
Copyright
Preface
Acknowledgements
1 Key principles
Basic radiology
Describing injuries
References
2 Particular paediatric points
Bones in children are different–
Fracture sites,
Sports injuries–
Chest emergencies–
Child abuse: skeletal injuries–
References
3 Paediatric skull—suspected NAI
Normal anatomy
Analysis: suture recognition
References
4 Adult skull
Anatomy
Analysis: false positive diagnoses
Analysis: recognising a fracture
A frequent pitfall
References
5 Face
Normal anatomy: midface & orbit
Normal anatomy: mandible
Analysis: the checklists
The common injuries
Pitfalls
References
6 Shoulder
Standard radiographs
Normal anatomy
Analysis: the checklists
The common fractures–
The common dislocations,,
Uncommon but important injuries
Pitfalls
References
7 Paediatric elbow
Anatomy
Analysis: four questions to answer
The common injuries
Rare but important injuries
Pitfalls
References
8 Adult elbow
Normal Anatomy
Analysis: three questions to answer
The common injuries
A rare but important injury
Pitfalls
References
9 Wrist & distal forearm
Normal anatomy
Analysis: the checklists
The common fractures
Subluxations and dislocations
Rare but important injuries
Normal variants that can mislead
References
10 Hand & fingers
Normal anatomy
Analysis: the checklist
The common injuries
Uncommon but important injuries
Pitfalls
References
11 Cervical spine
Normal anatomy
Analysis: the checklists
The common injuries
Pitfalls
References
12 Thoracic & lumbar spine
Normal anatomy
Analysis: the checklists
The common injury
Less frequent but important injuries
Pitfalls
References
13 Pelvis
Normal anatomy
Analysis: the checklist
Common fractures, high energy
Common fractures, low energy
Sports injuries: specific avulsions–
Pitfalls
References
14 Hip & proximal femur
Normal anatomy
Analysis: the checklists
The common injuries
Uncommon but important injuries
Pitfall
References
15 Knee
Normal anatomy
Analysis: the checklists
The common fractures
Small fragments around the knee
A common dislocation
Infrequent but important injuries
Pitfalls
References
16 Ankle & hindfoot
Normal anatomy
Analysis: the checklists,,
Common fractures/torn ligaments
Ligamentous injuries
Infrequent but important injuries
Pitfalls
References
17 Midfoot & forefoot
Normal anatomy
Analysis: the checklists
The common fractures
Infrequent but important fractures
Dislocations/subluxations
Pitfalls
References
18 Chest
Normal anatomy
Analysis: the checklists
Ten clinical problems
References
19 Abdominal pain & abdominal trauma
The AXR—its usefulness
Analysis: plain film checklists
The common problemsInfrequent but important problems
References
20 Penetrating foreign bodies
Appearances on plain radiographs
Suspected foreign bodies
References
21 Swallowed foreign bodies
The most common foreign bodies
Infrequent but important FBs
References
22 Test yourself
Test Yourself—answers
23 Glossary
Index
Copyright
SAUNDERS an imprint of Elsevier Limited © 2015,
Elsevier Limited. All rights reserved.
First edition 1995 WB Saunders Ltd Second edition 2005
Elsevier Ltd
Third edition 2015
The right of Nigel Raby, Laurence Berman, Simon Morley
and Gerald de Lacey to be identified as authors of this work
has been asserted by them in accordance with the
Copyright, Designs and Patents Act 1988.
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This book and the individual contributions contained in it
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as may be noted herein).
Notices
Knowledge and best practice in this field are
constantly changing. As new research and
experience broaden our understanding, changes
in research methods, professional practices, or
medical treatment may become necessary.
Practitioners and researchers must always rely on
their own experience and knowledge in evaluating
and using any information, methods, compounds,
or experiments described herein. In using such
information or methods they should be mindful of
their own safety and the safety of others,
including parties for whom they have a
professional responsibility.
With respect to any drug or pharmaceutical
products identified, readers are advised to check
the most current information provided (i) on
procedures featured or (ii) by the manufacturer of
each product to be administered, to verify the
recommended dose or formula, the method and
duration of administration, and contraindications.
It is the responsibility of practitioners, relying on
their own experience and knowledge of their
patients, to make diagnoses, to determine dosages
and the best treatment for each individual patient,
and to take all appropriate safety precautions.
To the fullest extent of the law, neither the
Publisher nor the authors, contributors, or
editors, assume any liability for any injury and/or
damage to persons or property as a matter of
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any use or operation of any methods, products,
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herein.
ISBN: 978-0-7020-4232-4
e-book ISBN: 978-0-7020-5031-2
Printed in China
Last digit is the print number: 9 8 7 6 5 4 3 2 1
Preface
This is not a book of orthopaedic radiology. It is a book
designed solely to assist with the accurate assessment of
the plain radiographs obtained in the Emergency
Department. Since the second edition was published in
2005 we have listened to the feedback from our numerous
teaching courses and to those working in our Emergency
Departments. Also, we recognise the plain film needs of
present day radiologists in training. As a consequence we
have placed a renewed emphasis on illustrating normal
skeletal anatomy by utilising skilful and clarifying artworks.
We have separated the common everyday injuries from
those that occur much less frequently. First and foremost,
we have adhered to our primary objective which is to assist
all those who read Emergency Department radiographs and
who ask the question… “at first glance these images look
normal to me—but how should I check them out in a logical
and systematic manner?”
The previous edition of the Survival Guide has proven to
be helpful to Emergency Department doctors, Emergency
Nurse Practitioners, Radiologists in training, Reporting
Radiographers, and to General Practitioners working on
their own in remote locations. We hope that this edition,
with its improvements in content, in anatomical detail, in
design and in layout, will once again assist all those who
read, report, and depend upon accurate plain film
interpretation in the Emergency Department.
Nigel Raby, Laurence Berman, Simon Morley, Gerald de Lacey
January 2014
Acknowledgements
We owe a prodigious amount of thanks to key individuals
without whom this third edition would not have been
completed. Claire Wanless created the new design and her
editorial guidance has been masterly and absolutely
invaluable. Philip Wilson produced the exquisite drawings
that are a key part of each and every chapter. Jeremy
Weldon, Consultant radiographer at Northwick Park
Hospital helped us with the illustrative cases and he
carried out the laboratory work on penetrating and
swallowed foreign bodies. Dr Denis Remedios, Consultant
radiologist at Northwick Park Hospital provided many
original
suggestions.
Michael
Houston,
senior
commissioning editor at Elsevier Ltd, prompted us to
produce this third edition and facilitated and assisted us in
our endeavours.
Our thanks are also due to a large and anonymous group,
comprising doctors, radiographers, and radiologists in
training who have attended our courses (www.radiologycourses.com and www.xraysurvivalguide.org), and through
their constructive feedback have stimulated us to enhance
numerous aspects, both large and small, in every chapter.
“That is the essence of science:
ask an impertinent question and you are on the way to a
pertinent answer.”
J. Bronowski, The Ascent of Man, 1973.
1
Key principles
Basic radiology
The radiographic image 2
Fracture lines: usually black, but sometimes white 3
Fat pads and fluid levels 3
The principle of two views 4
Important information: patient position 5
Assessing the radiographs: discipline is essential 5
Describing injuries
Fractures of the long bones 6
Dislocations 9
Introduction
Patients with traumatic injuries can be placed
into one of three major groups. The imaging
approach will differ between these groups.
Polytrauma (in which one injury may be
life threatening)
▪ Imaging:
Strict local protocols and algorithms utilising
early ultrasound (US) and/or multidetector
computed tomography (CT). The use of plain
film radiology in the Emergency Department
(ED) is generally limited1–4.
Multiple injuries (none of which is life
threatening)
▪ Imaging:
Plain film radiology is utilised in the ED.
Single injury (not life threatening)
▪ Imaging:
Plain film radiology is the principal imaging
investigation.
This book describes the assessment and
interpretation of the plain radiographs that are
customarily obtained in patients who have not
sustained a life threatening injury.
Basic radiology
The radiographic image
The tissues that lie in the path of the X-ray beam absorb (ie
attenuate) X-rays to differing degrees. These differences
account for the radiographic image.
Radiograph of a chicken leg (bone) partially
submerged in a layer of vegetable oil (fat) floating
on water (soft tissue). Note the difference in the
blackening of the X-ray film due to absorption by
the different tissues.
Fracture lines: usually black, but
sometimes white
When a fracture results in separation of bone fragments,
the X-ray beam that passes through the gap is not absorbed
by bone. This results in a black (ie lucent) line on the
radiograph.
On the other hand, bone fragments may overlap or
impact into each other. The resultant increased thickness of
bone absorbs more of the X-ray beam and so results in a
white (ie sclerotic or denser) area on the radiograph.
Three fractures. On the left the fragments are
distracted and the fracture shows as a dark black
line. In the centre the fragments overlap resulting
in a dense region on the radiograph. On the right
the fragments are impacted, also producing a
dense region.
Fat pads and fluid levels
There are radiological soft tissue signs which can provide a
clue that a fracture is likely. These include displacement of
the elbow fat pads (see pp. 97 and 102), or the presence of
a fat–fluid level at the knee joint (see pp. 248–249).
The principle of two views
‘One view only is one view too few’
Many fractures and dislocations are not detectable on a
single view. Consequently, it is normal practice to obtain
two standard projections, usually at right angles to each
other. The example below shows two views of an injured
finger.
At sites where fractures are known to be exceptionally
difficult to detect (for example a suspected scaphoid
fracture), it is routine practice to obtain more than two
views.
Injured finger.
The true extent of the injury is only evident on
the lateral view.
Important information: patient
position
Knowledge of the patient's position during radiography is
essential. A radiograph obtained with the patient lying
supine may produce a very different appearance when
compared with the image acquired with the patient erect.
Example 1.
Injured knee. Patient supine. A fat–fluid level in
the suprapatellar bursa (p. 249) will only be seen
when the radiograph is obtained with a horizontal
X-ray beam. A vertical beam radiograph will not
demonstrate the fat–fluid level.
Example 2.
A small pneumothorax will usually be detectable
at the apex of the lung on an erect chest X-ray
(CXR). On a supine CXR you need to look much
lower down, ie around the heart, the diaphragm,
and at the costophrenic angle5.
Assessing the radiographs: discipline
is essential
Missed injuries are common following trauma6–9. Detection
of a fracture, and the components of a complex injury,
depends on adherence to three cardinal rules:
▪ Rule 1. Always analyse both views.
▪ Rule 2. Develop a systematic step-by-step checking
process for each radiograph even if a single abnormality is
obvious. Two associated abnormalities often occur. The
major danger: you can be seduced by the satisfaction of
search phenomenon (“Yes—I have found the abnormality!”
), and consequently a second important abnormality is
overlooked.
▪ Rule 3. Check whether radiographs from the past exist. A
change in appearance will often assist you in recognising
an important abnormality. Similarly, an unchanged
appearance may stop you from erroneously diagnosing a
new injury or fracture10.
Describing injuries
Fractures of the long bones
The radiographic appearance of a fracture needs to be
described in a consistent style using accepted terminology.
Imagine that you are describing a fracture of a long bone to
the surgeon over the telephone11–13. These are the features
the surgeon will want you to describe—simply and
accurately:
▪ Site.
▪ Closed or open.
▪ Fragments.
▪ Direction of the fracture.
▪ Articular surface involvement.
▪ Position of the two major fragments.
▪ Angulation.
▪ Rotational deformity.
Site.
Specify which bone and which part of the bone.
The shaft of a long bone is divided into thirds:
▪ Proximal.
▪ Middle.
▪ Distal.
Left: Fracture of distal third.
Right: Fracture at junction of proximal and
middle thirds.
Closed or open.
▪ Closed: the fracture has not punctured the skin;
no open wound (left).
▪ Open: the bone has pierced the skin (right).
Also referred to as a compound fracture.
Fragments.
▪ Comminution: more than two fragments (left).
▪ Impaction: one fragment is driven into the other
(right).
Direction of the fracture.
▪ Transverse: at right angles to the long axis of
the bone (left).
▪ Oblique: at an angle of less than 90° to the long
axis of the bone (middle).
▪ Spiral: curving and twisting along the bone
(right).
Articular surface involvement.
If a joint surface is involved the fracture is intraarticular.
Position of the two major fragments.
Displaced or undisplaced.
Displacement is always described in relation to
the distal fragment.
▪ Lateral displacement (left)
▪ No displacement (middle two images)
▪ Posterior displacement (right)
Angulation.
Describe11,14 in relation to the distal fragment.
Refer either to the direction in which the apex of
the fracture points or to the direction of tilt of the
distal fragment. Describing the direction of tilt
may be easiest, as follows:
▪ Lateral tilt (left)
▪ Medial tilt (middle)
▪ Anterior tilt (right)
Rotational deformity.
A fragment has rotated on its long axis. Rotation
may be external (left) or internal (right).
Spontaneous correction is rare and surgery is
usually required.
NB: Rotation of a fragment on its long axis is
diagnosed most reliably by clinical examination.
However, fragment rotation may be evident on
the radiographs.
Dislocations
Precise use of language is important when describing
subluxations and dislocations.
Subluxation
The joint surfaces are no longer congruous but
the articular surface of one bone maintains some
contact with the articular surface of the adjacent
bone.
Example: inferior subluxation of the humeral
head.
Dislocation
The articular surfaces at the joint have lost all
contact with each other.
Example: inferior dislocation of the humeral
head.
Normal joint
For reference.
References
1. Pohlenz O, Bode PJ. The trauma emergency room: a
concept for handling and imaging the polytrauma
patient. Eur J Radiol. 1996;22:2–6.
2. Hessmann MH, Hofmann A, Kreitner KF, et al. The
benefit of multislice CT in the Emergency Room
management of polytraumatized patients. Acta Chir
Belg. 2006;106:500–507.
3. Kam CW, Lai CH, Lam SK, et al. What are the ten
new commandments in severe polytrauma
management? World J Emerg Med. 2010;1:85–92.
4. The Royal College of Radiologists. Standards of
practice and guidance for trauma radiology in
severely injured patients. The Royal College of
Radiologists: London; 2011.
5. de Lacey G, Morley S, Berman L. The Chest X-Ray:
A Survival Guide. Saunders Elsevier: Philadelphia;
2008.
6. Roberts CS. The missed injury in our big, flat, spiky
world. Editorial. Injury. 2008;39:1093–1094.
7. Guly HR. Diagnostic errors in an accident and
emergency department. Emerg Med J. 2001;18:263–
269.
8. Pinto A, Brunese L. Spectrum of diagnostic errors in
radiology. World J Radiol. 2010;28:377–383.
9. Gatt ME, Spectre G, Paltiel O, et al. Chest
radiographs in the emergency department: is the
radiologist really necessary? Postgrad Med J.
2003;79:214–217.
10. Keats TE, Anderson MW. Atlas of normal Roentgen
variants that may simulate disease. 9th ed. Elsevier
Health Sciences; 2012.
11. Pitt MJ, Speer DP. Radiologic reporting of skeletal
trauma. Radiol Clin North Am. 1990;28:247–256.
12. Renner RR, Mauler GG, Ambrose JL. The radiologist,
the orthopedist, the lawyer, and the fracture. Semin
Roentgenol. 1978;13:7–19.
13. Adam A, Dixon AK, Grainger RG, Allison DJ.
Grainger & Allison's Diagnostic Radiology. 5th ed.
Churchill Livingstone/Elsevier; 2008.
14. Gaskin JSH, Pimple MK, Wharton R, et al. How
accurate and reliable are doctors in estimating
fracture angulation? Injury. 2007;38:160–162.
2
Particular paediatric
points
Bones in children are different
Child versus adult 12
The end of a long bone in a child 13
Fracture sites
Epiphyseal–metaphyseal (Salter–Harris) fractures 14
Metaphyseal–diaphyseal fractures 18
Diaphyseal fractures 20
Toddler's fracture 22
Sports injuries
Stress fractures 24
Avulsion injuries 26
Chondral & osteochondral injuries 28
Chest emergencies
Inhaled foreign body 30
Child abuse
Under- and over-diagnosis of non-accidental injury
(NAI) 31
Radiographic features suggestive of NAI 32
Radiographic features highly suggestive of NAI 32
Paediatric Points addressed in
other chapters
Chapter 3, pp. 35–46: Skull—suspected NAI.
Chapter 6, pp. 92–93: Shoulder.
Chapter 7, pp. 95–114: Elbow.
Chapter 13, pp. 214–215, 224–226: Pelvis.
Chapter 17, pp. 298, 304–305: Foot.
Chapter 21, pp. 350–351, 358–359: Swallowed
foreign bodies.
Bones in children are different1–4
“A child is not a small adult …”
This truism is particularly important in relation to paediatric
bone injuries1
Child versus adult
There are three major differences between a child's and an
adult's skeleton2–4.
1. Children have growth plates that:
□ have the consistency of hard rubber and act, in part,
as shock absorbers
□ protect the joint surface from sustaining a
comminuted fracture
□ are weaker than the ligaments. Consequently the
epiphysis will separate before a dislocation (ie
ligamentous disruption) occurs.
2. Children have a thick periosteum that:
□ is not only thick but very, very, strong
□ acts as a hinge, which inhibits displacement when a
fracture occurs.
3. Children's bones have an inherently different structure
to adults' bones, being:
□ less brittle
□ flexible, elastic, and plastic, allowing an injured bone
to bend or to buckle.
The growth plate (ie the physis) is a site of
weakness.
The very strong periosteum inhibits and
impedes displacement at the site of the fracture.
The end of a long bone in a child
You need to be familiar with the normal radiographic
appearance of the ends of the long bones in children. This
will help you to detect the important injuries and will also
protect you from labelling a normal developmental
appearance as being abnormal.
A persistent lucent line is normal
A child's long bone grows in length initially by forming
layers of cartilage and gradually converting that cartilage
into bone. This layering process takes place at the end of
the bone at the site of the physis (also called the epiphyseal
plate or the growth plate). The physis is made of cartilage
and lies between the epiphysis and the diaphysis. Cartilage
is lucent on a radiograph. The cartilaginous physis remains
as a radiographic lucency until the child reaches skeletal
maturity and stops growing. At that time the lucent physis
fuses to the metaphysis (and also to the epiphysis). When
fusion occurs the linear lucency that was the physis
disappears.
Parts of the skeleton are not missing
An epiphysis is a secondary centre of ossification at the end
of a long bone. Each epiphysis is initially composed solely
of cartilage. As a consequence it looks as though nothing is
there (take a look at a new born baby's elbow region). Of
course each of the epiphyses is present, but present as a
radiolucent blob of cartilage. These invisible blobs enlarge
slowly with age. Eventually they begin to ossify at their
centres and become visible. Finally, these blobs of bone will
fuse to the physis at maturity.
Normal wrist (left to right) in a young male at
ages: 7 months; 5 years; 10 years; 14 years.
Gradually the invisible epiphyses become ossified
and consequently visible.
Fracture sites1,3
“The key to accurate diagnosis is a precisely accurate
assessment of the radiographs.”2
The anatomical regions in a long bone.
Epiphyseal–metaphyseal (Salter–
Harris) fractures
The growth plate (the physis) is a very vulnerable
structure. The joint capsule, the surrounding ligaments and
the muscle tendons are all much stronger than the
cartilaginous physis.
A shearing or avulsion force applied to a joint is most
likely to result in an injury at the weakest point, ie a
fracture through the growth plate.
Most growth plate injuries will heal well without any
resultant deformity. However, in a few patients, failure to
recognise a growth plate injury may result in suboptimal
treatment with a risk of premature fusion resulting in limb
shortening. If only a part of the growth plate is injured,
unequal growth may lead to deformity and disability.
The cartilaginous growth plate (the physis) is a
weak and vulnerable site in a long bone.
Injuries affecting the physis are common.
The Salter–Harris classification
This classification links the radiographic appearance of the
fracture to the clinical importance of the fracture. A Salter–
Harris type 1 injury has a good prognosis whereas a Salter–
Harris type 5 injury has a poor prognosis.
Salter–Harris fractures.
Type 1 is a fracture restricted to the growth
plate.
Types 2–4 represent various patterns of fracture
involving the growth plate and the adjacent
metaphysis and/or epiphysis.
Type 5 is an impaction fracture of the entire
growth plate.
Salter–Harris fractures
How to remember the Salter–Harris (SH)
classification
SH 1
=S
is Separated (a widened physis)
SH 2
=A
is Above the growth plate
SH 3
=L
is beLow the growth plate
SH 4
=T
is Through the growth plate
=E
is for nothing!
=R
has a Rammed together growth plate
SH 5
Salter–Harris fracture: five types
Type 1.
Fracture restricted to the growth plate. In this
patient the epiphysis is displaced posteriorly.
Note: Many type 1 fractures do not show
displacement of the epiphysis, making it
impossible to detect the injury to the growth
plate from the radiographs. Prognosis in these
cases is invariably very good.
Type 2.
Fracture through the metaphysis that extends
into the growth plate.
Type 3.
Fracture through the epiphysis that extends into
the growth plate.
Type 4.
Fracture that involves the growth plate and the
epiphysis and the metaphysis.
Type 4 runs the risk of premature fusion of part
of the growth plate.
Type 5.
Impaction fracture of the entire growth plate.
There is little or no malalignment and it is usually
impossible to make the diagnosis on the initial
radiographs. This is the most significant of the
Salter–Harris injuries. The plate may fuse
prematurely with consequent limb shortening.
The
diagnosis,
and
consequently
optimal
management, depends on a high degree of
suspicion following clinical examination.
Metaphyseal–diaphyseal fractures
When a child's long bone is subjected to a longitudinal
compression force (such as a fall on an outstretched hand),
this can result in two common but different types of injury
in the region of the metaphysis and proximal diaphysis.
▪ Torus fracture
▪ Greenstick fracture
Torus fracture.
Results from a longitudinal compression force
with little or no angulation. The axial loading is
distributed evenly across the metaphysis (right).
There are microfractures of the trabeculae at the
injured site.
The commonest sites for a torus fracture are
the distal radius and/or ulna.
The fracture is often subtle and appears as a
ripple, a wave, an indent or a slight bump/bulge
in the cortex. The bulge may be seen at both
cortices or at one cortex only.
Fractures: some synonyms3
▪ Torus fracture = Buckle fracture
▪ Greenstick fracture = Angled Buckle fracture
The word “Torus” is derived from the latin word
for a bulge.
Greenstick fracture.
A Greenstick fracture results from an angulation
force.
There is a break in the cortex on one side of the
bone. The opposite cortex remains intact. This
occurs because of the very thick and elastic
periosteum.
There is usually some angulation at the fracture
site, although this can be slight and subtle.
Diaphyseal fractures6,7
A diaphyseal fracture: a break in the shaft of a long bone,
well away from an epiphysis.
Diaphyseal fracture.
PS: Another injury is also present. (Have you
identified the additional abnormality? See p. 104.)
Incomplete diaphyseal fracture—the
plastic bowing fracture1,7.
A child's bone may bend or bow with no obvious
break in the cortex.
Traumatic bowing occurs as follows: a
compression force extends along the longitudinal
axis of the bone. The concave surface develops a
series of microfractures causing the bone to
bend. The compression force is insufficient to
cause a transverse fracture.
Plastic bowing fracture of the ulna.
There is an associated Greenstick fracture of the
radius.
Plastic bowing fractures usually involve the
radius or ulna but may affect other long bones
including the femur, fibula, tibia, and occasionally
the clavicle.
A plastic bowing fracture is sometimes known
as a “bone bending fracture”.
Diagnosing plastic bowing fractures.
Sometimes a bowing (or bending) injury can be
difficult to diagnose with certainty because
differences in radiographic positioning of the
normal forearm bones can mimic a slightly bent
bone. If you think that an injured bone is slightly
bent then this justifies obtaining images of the
opposite normal side. Comparison may make the
bowing of the injured bone obvious.
A plastic bowing fracture may only be
recognised in retrospect when subsequent
radiographs show remodelling on the concave
side of the bone.
Note: do not expect profuse periosteal new
bone formation during healing following a plastic
bowing fracture6. It is more common for
remodelling alone to occur.
Toddler's fracture8–10
The classic toddler's fracture involves the shaft of the tibia.
Usually it occurs in a child aged 9 months to 3 years. The
child falls with one leg fixed and a twisting injury occurs
resulting in a spiral fracture of the tibia.
Invariably, the fracture is undisplaced and is frequently
very difficult to visualise on the initial radiographs.
Sometimes it will only be demonstrated on an additional
oblique projection, or on a radionuclide study. If a repeat
radiograph is obtained 10–14 days after the injury
periosteal new bone will be present.
Toddler's fracture.
The undisplaced fracture spirals along the shaft
of the distal tibia.
Clinical impact guideline: acute
fractures in a limping toddler
The most common fracture is a spiral fracture of
the shaft of the tibia—a “Toddler's fracture”.
Other acute fractures do occur in limping
toddlers. Fractures of the femur, cuboid,
calcaneum, and distal fibula have all been
described8–13. Different falling or stumbling
mechanisms create particular forces that affect
specific bones.
Because of the very similar history of a
seemingly mild injury, and because all of these
fractures can be radiographically very difficult to
detect, it has been suggested that the collective
term “Toddler's fractures” should be applied to
this entire group of injuries10. This suggestion has
gone unheeded.
The singular term “Toddler's fracture” persists,
remains a specific term, and is applied solely to
the classic spiral fracture of the tibia.
Clinical impact guideline: a limping
toddler—what to do?
If a child refuses to weight-bear or is well but
limping, then the possibility of a Toddler's
fracture needs to be considered. If the tibia
appears normal8,13 on the digital images—
including additional oblique views—then there
are two possible courses of action:
▪ Scintigraphy will show whether a fracture is or
is not present
Or:
▪ Adopt an expectant approach. Toddler's
fractures heal without any particular treatment.
In a limping but otherwise well child who has
sustained a Toddler's fracture, plain film
radiography 10–14 days later will show evidence
of the healing fracture (ie periosteal new bone
formation).
Toddler's fracture.
The original radiograph (left) obtained when the
child first started to limp was passed as normal.
Ten days later the radiograph (right) shows the
fracture as well as extensive periosteal new bone
extending along the full length of the tibia.
Sports injuries14–17
Sports injuries affecting young children and adolescents
are common. Some of these patients will attend the
Emergency Department complaining of acute or chronic
pain.
Acute Injuries
Acute fractures follow the same patterns as those that
occur as a result of accidental trauma in the playground or
elsewhere. Salter–Harris growth plate fractures, Torus and
Greenstick fractures, and plastic bowing fractures are
described on pp. 14–21.
Chronic injuries
A chronic sports injury may cause diagnostic difficulty to
the unwary. Three skeletal injuries occur: stress fractures,
avulsion fractures, and osteochondral injuries.
Stress fractures15–20
Most stress fractures occur in the lower limbs as a
consequence of weight bearing stresses in runners and
footballers. Other activities can affect the ribs and upper
limbs. The appearances of stress fractures on plain
radiographs do vary.
Scintigraphy will detect a stress fracture when the plain
radiographs appear normal.
MRI is the most sensitive test for identifying fractures in
their very earliest stages19. If there is clinical suspicion of a
stress fracture and the plain radiographs appear normal
then MRI is the imaging test of choice; it will provide the
maximum detail in relation to the fracture.
Stress fractures14,15,17,18
Bone
Site
Recognised activities
Pelvis
Pubic ramus
Distance runners, gymnasts
Femur
Shaft/neck
Dancers
Tibia
Proximal third or
junction of mid &
dist thirds
Runners, footballers, dancers
Fibula
Distal third
Runners, footballers
Navicular
Centre
Runners, jumpers, footballers
Calcaneum
Metatarsals
Jumpers
Shafts
Sesamoids
Dancers, runners, footballers
Runners
Wrist
Growth plate
Gymnasts
Vertebrae
L4 or L5
Pars interarticularis
Dancers, fast bowlers, gymnasts,
tennis players, USA football
linemen
Ribs
First rib
Throwers
Note: Stress fractures are not limited to these sites nor these activities
only.
Radiographic appearances of stress fractures
If not recognised or treated, a stress fractures will sometimes progress to a
complete and displaced fracture.
Runner with foot pain (above). Fluffy callus is
present around the stress fracture of the third
metatarsal.
Athlete with leg pain (right). Band of
sclerosis across the diaphysis of the tibia and
periosteal new bone along the medial margin.
Stress fracture.
Avulsion injuries15,16,21,22
Apophyseal fractures occur almost exclusively in athletic
children and adolescents21,22. Hurdling, sprinting, soccer,
and tennis are the principal at-risk activities.
An apophysis is a secondary ossification centre that is not
related to a joint surface. Consequently, an apophyseal
fracture is a growth plate injury and is analogous to a
Salter–Harris type 1 fracture. Apophyses are often the sites
of tendonous insertions and avulsion occurs as a result of a
violent or repetitive muscle pull. The most common
avulsion sites are:
▪ Ischial tuberosity
▪ Anterior inferior iliac spine (AIIS)
▪ Anterior superior iliac spine (ASIS)
▪ Humerus: medial epicondyle. (Incidentally this is not an
apophysis. It is an epiphysis.) Nevertheless, avulsion is
fairly common at the elbow. It represents the so-called
“little leaguer's elbow” because throwing sports can cause
the medial epicondyle to be pulled off. These activities
include baseball pitching.
For additional detail about avulsion injuries at particular
sites see:
▪ Pelvis—p. 224.
▪ Elbow—p. 105.
▪ Midfoot and forefoot—p. 298.
An apophysis can be avulsed from the parent
bone by repetitive vigorous muscle contraction
(left). Similarly, the medial epicondyle secondary
centre can be detached (right) during throwing
sports. Also, this avulsion is often consequent
when a violent valgus stress is sustained during a
fall onto an outstretched hand.
Pelvic avulsion injuries are common.
Radiographic appearances …
Acute:
▪ An ossified apophyseal fragment is detached
and visible
Chronic:
▪ Variable appearances:
□ Apophyseal irregularity
□ Sclerotic and fragmented apophysis
□ Exuberant callus
□ Calcification in a surrounding haematoma
▪ The Golden Rule:
□ Always compare the painful side with the
opposite and normal side
Two young athletes with hip pain.
Avulsed femoral apophysis (left). Avulsed right
AIIS (right).
Chondral & osteochondral injuries14,15
Repetitive trauma with impaction of one cartilage covered
bone on another can cause fissuring within the underlying
bone. A defect may result and a lucency within the affected
bone can become visible on the radiograph. The lesion is
termed osteochondritis dissecans (OCD). Sometimes a bone
fragment becomes loose and may be seen within the joint.
The sites most commonly affected are the:
▪ lateral aspect of the medial femoral condyle
▪ medial and lateral margins of the talus
▪ capitellum of the distal humerus.
OCD in the medial condyle of the femur
(arrows). The position is typical for this lesion.
Normal smooth cortex of the dome of the talus
(left).
Osteochondral fracture of the lateral aspect of
the talar dome (right).
Acute or recently acquired osteochondritis
dissecans (left). Old OCD lesion, shown by an
irregular defect in the articular surface of the
talus (right).
The talar dome is a vulnerable site.
Summary: osteochondritis dissecans
Description. An area of bone at a joint surface
becomes separated from the rest of the bone
surrounding it. The bone fragment, with its
cartilage cap, becomes loose. It represents a
fragment lying within a crater. The fragment
may break off and become completely free
within the joint.
Aetiology. Several different possibilities have
been suggested including a genetic disposition
as the primary cause. The blood supply to the
affected bone fragment is damaged. There is
little doubt that repetitive trauma with
impaction of one bone on another is the major
cause in many instances14,15.
Common sites. Medial condyle of the distal
femur; lateral or medial aspects of the dome of
the tarsal talus; the capitellum of the distal
humerus.
Symptoms. Joint pain. Sometimes a detached
fragment lying loose within the joint will cause
the joint to lock.
Additional imaging. MRI will determine
whether the articular cartilage overlying the
bone fragment is intact. This information can
influence the precise choice of management of a
particular lesion.
Chest emergencies23–26
Children attend the Emergency Department with upper and
lower airway problems including coughing, chest trauma,
wheezing, and pneumonia. The plain film radiology of these
problems is addressed in The Chest X-Ray: A Survival
Guide24.
For swallowed foreign bodies, see pp. 349–362.
Inhaled foreign body
Infants and toddlers are at risk of foreign body aspiration,
frequently unwitnessed. The most commonly inhaled
foreign body is food, often a peanut23,25,27–30. A history of
choking is usually obtained. Common clinical signs include
coughing, stridor, wheezing and sternal retraction. Rapid
recognition and treatment are essential.
Radiography
If the child is able to cooperate then a frontal chest X-ray
(CXR) should be obtained following a rapid forced
expiration. Air trapping on the affected side (due to
obstruction of the airway) is then more obvious.
Fluoroscopy is an excellent way of observing whether
there is unilateral air trapping.
Possible findings on the CXR:
▪ Obstructive atelectasis—areas of collapse/consolidation.
▪ Obstructive emphysema—a unilateral hypertransradiant
lung, due to air trapping. The affected lung appears
blacker and larger than the opposite normal side.
▪ Normal appearances. This is not necessarily reassuring. If
the clinical suspicion remains that a foreign body has been
inhaled then an emergency MRI28 or bronchoscopy is
essential.
An inhaled peanut in the right main bronchus.
Inspiration film (left): the right lung is
hypertransradiant (ie blacker) compared with the
left. Following rapid expiration (right), air
trapping on the right is now obvious. Mediastinal
displacement to the left is evident. Note: food
(including peanuts) will not be visible on a
radiograph.
Child abuse: skeletal injuries31–34
The possibility of non-accidental injury (NAI) must be
considered in all injured children presenting to the
Emergency Department. No socioeconomic group or race is
exempt.
▪ 50% of cases of NAI occur before the age of 1 year.
▪ 80% of cases occur before the age of 2 years.
Normal radiographs do not exclude the diagnosis. In 50%
of proven cases of NAI the radiographs are normal.
Nevertheless, fractures are the second most common
finding in child abuse; second, after cutaneous
abnormalities such as bruises and contusions.
Clinical and radiological involvement in
suspected NAI
Usual requirements/practice:
▪ Early involvement of the designated paediatric
team.
▪ The paediatric team takes responsibility for
instigating and organising a skeletal survey
when they deem this to be indicated.
▪ Specialist paediatric radiologists review and
report on all of the radiographs obtained.
▪ All radiographs are double-read by two
paediatric radiologists.
Under- and over-diagnosis of NAI31,34
Failure to diagnose a particular injury as being suggestive
of abuse in a child attending the Emergency Department
can have devastating consequences. Similarly, an overdiagnosis of NAI can be highly detrimental for the child and
for those who are looking after the child. A particular area
of difficulty is the evaluation of an infant's or toddler's skull
radiographs because of the skull sutures (see pp. 36–45).
Radiological pitfalls in the diagnosis of NAI in
the Emergency Department
1. Failure to consider the possibility of child abuse.
2. Ignorance of the particular or specific radiological
features (ie appearance or position) that should raise the
suspicion of NAI.
3. Normal skeletal variants misinterpreted as evidence of
NAI. These include accessory skull sutures, physiological
periosteal reaction, and normal metaphyseal variants35.
4. Suboptimal imaging.
5. Other pathological processes, such as osteogenesis
imperfecta, osteomyelitis and scurvy may simulate some
of the skeletal features of NAI.
Radiographic features suggestive of
NAI31,32,34
Subperiosteal new bone formation (right).
Periosteal
reactions
may
result
from
subperiosteal bleeding due to punching, shaking
or squeezing. Periosteal reaction and callus
formation can occur within a few days of trauma,
but will not be present on the actual day of the
injury. If new bone is present then some days or
weeks have elapsed since the injury.
More than one fracture (not shown).
Particularly suspicious if the stages of evolution
of the fractures appear to be different, since this
indicates that the injuries have occurred at
different times. For example one fracture may
show some faint periosteal new bone, whereas
another may demonstrate mature callus.
Radiographic features highly
suggestive of NAI31,32,34
A small fracture at the corner of a
metaphysis of a long bone.
This is known as a corner fracture.
Skull fractures that are wide (as in this
child), complex and involving both sides of
the skull, or involving both the occiput and
the vertex.
A transverse fracture of the distal
metaphysis of a long bone.
This has been likened to a bucket handle, hence
the term “bucket handle fracture”.
Fractures involving the posterior
aspects of the ribs close to the spine.
These occur when a child is held by the chest and
shaken or squeezed.
▪ Rib fractures in children under the age of 2
years are usually due to NAI.
▪ Rib fractures often result from very violent
shaking episodes—these have a recognised
association with brain injury.
Fractures of the pelvis, sternum, and
the vertebral transverse processes.
These are rarely caused by an accidental injury.
References
1. Kirks DR, Griscom NT. Practical pediatric imaging:
diagnostic radiology of infants and children. 3rd ed.
Lippincott Williams & Wilkins; 1998.
2. Conrad EU, Rang MC. Fractures and sprains. Ped
Clin North Am. 1986;33:1523–1540.
3. Swischuk LE. Subtle fractures in kids: how not to
miss them. Applied Radiology. 2002;31:15–19.
4. Kao SCS, Smith WL. Skeletal injuries in the
pediatric patient. Radiol Clin North Am.
1997;35:727–746.
5. Mizuta T, Benson WM, Foster BK, et al. Statistical
analysis of the incidence of physeal injuries. J
Pediatr Orthop. 1987;7:518–523.
6. Crowe JE, Swischuk LE. Acute bowing fractures of
the forearm in children: a frequently missed injury.
AJR. 1977;128:981–984.
7. Attia MW, Glasstetter DS. Plastic bowing type
fracture of the forearm in two children. Pediatr
Emerg Care. 1997;13:392–393.
8. Fahr MJ, James LP, Beck JR, et al. Digital
radiography in the diagnosis of Toddler's fracture.
South Med J. 2003;96:234–239.
9. Swischuk LE, John SD, Tschoepe EJ. Upper tibial
hyperextension fractures in infants: another occult
toddler's fracture. Pediat Radiol. 1999;29:6–9.
10. John SD, Moorthy CS, Swischuk LE. Expanding the
concept of the toddler's fracture. Radiographics.
1997;17:367–376.
11. Blumberg K, Patterson RJ. The toddler's cuboid
fracture. Radiology. 1991;179:93–94.
12. Laliotis N, Pennie BH, Carty H, et al. Toddler's
fracture of the calcaneum. Injury. 1993;24:169–170.
13. Donnelly LF. Toddler's fracture of the fibula. Am J
Roentgenol. 2000;175:922.
14. Long G. Imaging of paediatric sports injuries. RAD
Magazine. 1999;26:23–24.
15. Carty H. Sports injuries in children—a radiological
viewpoint. Arch Dis Child. 1994;70:457–460.
16. Anderson SJ. Lower extremity injuries in youth
sports. Pediatr Clin North Am. 2002;49:627–641.
17. Heyworth BE, Green DW. Lower extremity stress
fractures in pediatric and adolescent athletes. Curr
Opin Pediatr. 2008;20:58–61.
18. Daffner RH, Pavlov H. Stress Fractures: Current
Concepts. Am J Roentgenol. 1992;159:245–252.
19. Daffner RH. MRI of occult and stress fractures.
Applied Radiology. 2003;32:40–49.
20. Connolly SA, Connolly LP, Jaramillo D. Imaging of
sports injuries in children and adolescents. Radiol
Clin North Am. 2001;39:773–790.
21. Sundar M, Carty H. Avulsion fractures of the pelvis
in children: a report of 32 fractures and their
outcome. Skeletal Radiol. 1994;23:85–90.
22. El-Khoury GY, Daniel WW, Kathol MH. Acute and
chronic avulsive injuries. Radiol Clin North Am.
1997;35:747–766.
23. Swischuk LE, John SD. Emergency pediatric chest
radiology. Emerg Rad. 1999;6:160–169.
24. de Lacey G, Morley S, Berman L. The Chest X-Ray: A
Survival Guide. Saunders Elsevier: Philadelphia;
2008.
25. Chapman T, Sandstrom CK, Parnell SE. Pediatric
emergencies of the upper and lower airway. Applied
Radiology. 2012 [April] .
26. Carty H. Emergency Pediatric Radiology. SpringerVerlag; 2002.
27. Baharloo F, Veyckemans F, Francis C, et al.
Tracheobronchial foreign bodies: presentation and
management in children and adults. Chest.
1999;115:1357–1362.
28. Imaizumi H, Kaneko M, Nara S, et al. Definitive
diagnosis and location of peanuts in the airways
using magnetic resonance imaging techniques. Ann
Emerg Med. 1994;23:1379–1382.
29. Sersar SI, Rizk WH, Bilal M, et al. Inhaled Foreign
Bodies: Presentation, Management and value of
History and Plain Chest Radiography in Delayed
Presentation. Otolaryngology—Head and Neck
Surgery. 2006;134:92–99.
30. Zaupa P, Saxena AK, Barounig A, et al. Management
Strategies in Foreign-Body Aspiration. Indian J
Pediatr. 2009;76:157–161.
31. Offiah A, van Rijn RR, Perez-Rossello JM, et al.
Skeletal Imaging of child abuse (non-accidental
injury). Pediatr Radiol. 2009;39:461–470.
32. Ebrahim N. Patterns and mechanisms of injury in
non-accidental injury in children (NAI). SA Fam
Pract. 2008;50:5–13.
33. Kemp AM, Butler A, Morris S, et al. Which
radiological investigations should be performed to
identify fractures in suspected child abuse? Clin
Rad. 2006;61:723–736.
34. Carty H, Pierce A. Non-accidental injury: a
retrospective analysis of a large cohort. Eur Radiol.
2002;12:2919–2925.
35. Kleinman PK. Diagnostic imaging in infant abuse.
AJR. 1990;155:703–712.
3
Paediatric skull—
suspected NAI
Normal anatomy
Infants and toddlers—normal accessory sutures 36
The lateral SXR 37
The AP frontal SXR 38
The Towne's SXR 39
Analysis: suture recognition
The principal question: is it a suture or a fracture?
40
Be aware … 40
Assessing the radiographs 40
Suture recognition on the Towne's view 41
Suture recognition on the lateral view 42
Suture recognition on the AP view 44
A skull X-ray (SXR) continues to have an
important role when there is suspicion of nonaccidental injury (NAI) in an infant or a toddler1–3.
The primary indication for a SXR in these patients
is forensic3.
Be careful:
▪ Accessory sutures are common.
▪ Calling an accessory suture a fracture may lead
to an incorrect suggestion of NAI.
▪ Dismissing a fracture as an accessory suture
can have serious clinical consequences.
▪ To avoid mistakes:
□ Be aware of the positions of the common
accessory sutures.
□ Assess and interpret an infant's or toddler's
radiographs in a systematic step-by-step
manner.
The standard radiographs
▪ Lateral.
▪ AP frontal view.
▪ Towne's view.
The precise SXR views to be obtained will be
specified by the local protocol for NAI assessment
in infants and toddlers3.
Abbreviations
the sutures
C, coronal;
In, innominate;
L, lambdoid;
M, mendosal;
Met, metopic;
O, occipitomastoid;
P1 and P2, accessory parietal;
Sa, sagittal;
Sq, squamosal.
NAI, non-accidental injury.
Normal anatomy
Infants and toddlers—normal
accessory sutures
Evaluating the SXR in an infant or toddler presents unique
problems. Diagnostic confusion between sutures and
fractures may have serious consequences. A basic
understanding of the locations and variable appearances of
these sutures will help to reduce the likelihood of
misdiagnosis4–8.
A basic classification of skull sutures in infants and
toddlers
Grouping
The normal
sutures
Notes
Visible on the SXR in all
infants and toddlers –
persisting in all adults
Sutures
Sagittal, coronal,
lambdoid, squamosal,
and smaller sutures
around the mastoid
A normal
Visible on the SXR in all
developmental
infants and many toddlers
suture
– but not in adults
Innominate
The most
common
accessory
sutures
Metopic, accessory
parietal, mendosal
Visible on the SXR in some
infants and toddlers –
occasionally persisting to
adulthood
Normal accessory sutures and the radiographs on
which they are seen
Suture
Most
commonly Notes
seen on
Metopic
suture
Frontal √ √
The commonest accessory suture. It is also the
Towne's √
one that most commonly persists in older
children, and even in a few adults.
Accessory
parietal
suture
Towne's √ √
Frontal √
Lateral √
Mendosal
suture
Lateral √ √
Extends posteriorly from the lambdoid suture
Towne's √
on the lateral view. Passes medially on
Towne's view.
Innominate
suture
Lateral √ √
May be complete or incomplete. Occurs in
vertical, horizontal or oblique orientations.
Most commonly vertical.
Sometimes classified as an accessory suture
but best regarded as a normal
developmental suture because it is always
present in infants. As the child matures this
suture disappears.
The lateral SXR
The normal sutures. L = lambdoid suture; C
= coronal suture; M = mendosal; O =
occipitomastoid suture; Sq = squamosal suture;
In = innominate suture
Accessory parietal sutures. Can appear in
various positions (P).
Accessory parietal sutures vary in position. This
drawing does not correspond to any radiographic
projection. It shows the general positions and
direction of the more common incomplete
accessory parietal sutures (P1 and P2) when
looking down from above the cranium.
L = lambdoid suture;
C = coronal suture;
Sa = sagittal suture;
P = accessory parietal sutures.
The AP frontal SXR
Normal sutures on the frontal view.
L = lambdoid suture;
C = coronal suture;
Sa = sagittal suture;
Sq = squamosal suture.
Accessory suture—the metopic.
This suture divides the frontal bone into two
halves.
Met = metopic suture.
Accessory parietal sutures.
The drawing shows possible positions/sites of
accessory parietal sutures.
L = lambdoid suture;
Sa = sagittal suture;
Sq = squamosal suture;
P = accessory parietal suture.
The Towne's SXR
Normal sutures on the Towne's view.
L = lambdoid suture;
C = coronal suture;
Sa = sagittal suture;
Sq = squamosal suture;
FM = foramen magnum.
Accessory suture—the mendosal.
This accessory suture is situated in the occipital
bone. Very occasionally it is whole (ie complete).
More often it is incomplete. Very often it is
incomplete and on one side of the bone only.
M = mendosal suture;
L = lambdoid suture;
Sq = squamosal suture;
FM = foramen magnum.
Analysis: suture recognition
The principal question: is it a
suture or a fracture? 4–8
When assessing suspected non-accidental injury (NAI) in
young children, be very careful not to rush too swiftly to
judgement. Observing an abnormality is important. An
informed approach is then required when assigning a
particular significance to the abnormality9–12.
Be aware …
▪ Wide sutures are normal in neonates.
▪ Accessory sutures are common and are a part of normal
development. An awareness of the positions and
appearances of the common accessory sutures will help to
reduce errors of interpretation.
▪ The age at which an accessory suture closes is variable.
Accessory sutures are present in some older children. Very
occasionally they persist into adulthood.
▪ Radiography in a wriggling infant can be very difficult.
The Towne's view (injury to occiput) or the AP frontal view
(injury elsewhere) is frequently a technical compromise.
The head is often slightly rotated.
Assessing the radiographs
1. Trace every line seen on the two standard radiographs.
For each line ask yourself: is this a suture?
2. Whenever a lucent line is detected it is essential to
assess the two radiographs together. They form a
complementary pair.
3. Always correlate the findings with the clinical history
and the physical examination.
The importance of evaluating the two SXR
views as a pair. On the frontal SXR (left) the
lucent line (arrow) could be interpreted as an
accessory suture. The lateral view (right) shows
that the line (arrow) is much more extensive and
continues through to the temporal bone. This is a
fracture.
Suture recognition on the Towne's
view
Normal sutures present in all children.
Towne's view.
L = lambdoid suture;
C = coronal suture;
Sa = sagittal suture.
Mendosal suture. A mendosal suture (arrow)
can be present on both sides. It may be complete
or incomplete. Most commonly it is incomplete. M
= mendosal suture; L = lambdoid suture; Sq =
squamosal suture; FM = foramen magnum.
Suture recognition on the lateral view
Lateral view.
L = lambdoid suture;
C = coronal suture;
O = occipitomastoid suture;
Sq = squamosal suture;
In = innominate suture.
The sagittal and metopic sutures are not seen
on the lateral view because they lie in the midline
(ie parallel to the plane of the radiograph).
Squamosal
suture.
Extends
anteriorly,
separating the parietal bone from the temporal
bone. The usual appearance is of a pair of lines
(arrows) on the lateral projection (ie the left
squamosal suture and the right squamosal
suture). Invariably, the squamosal suture fades
away as it passes anteriorly.
Lambdoid suture. As it nears the base of the
skull (in the region of the mastoid bone) the
suture appears to be complex. This seemingly
tangled appearance is mainly caused by
overlapping of the normal occipitomastoid
sutures on the right and left sides. Don't worry
about this. Arising from the lambdoid suture
there will be:
▪ a normal suture, the squamosal suture.
▪ a normal developmental suture, the
innominate suture.
▪ sometimes, an accessory suture, the mendosal
suture.
Accessory parietal sutures (also known as
intraparietal sutures).
These are often best seen (arrow) on this view.
Suture recognition on the AP view
The sagittal and lambdoid sutures are well
shown. In addition an accessory parietal suture
(arrow) is also present.
The lambdoid suture meets the sagittal suture
in the midline.
On the frontal radiograph the sagittal suture
appears foreshortened.
Normal sutures on the frontal view.
This diagram also shows wormian
contained within the lambdoid sutures.
L = lambdoid suture;
C = coronal suture;
Sa = sagittal suture;
Sq = squamosal suture;
W = wormian bone.
bones
Wormian bones.
It is not uncommon to see one (or several)
wormian bones (W) on the AP projection, and
occasionially also on other projections. This is a
normal finding. A wormian bone is a small area of
the skull (sometimes as large as 1–2 cm in
diameter) within a suture. The bone is completely
surrounded by the lucent suture.
Metopic suture.
Where it meets the coronal suture, the sagittal
suture should stop. If it continues below this
point then the patient has a metopic suture. This
accessory suture divides the frontal bone into two
halves. The metopic suture (arrow) is the
commonest accessory suture in children.
Sometimes it persists into adulthood. Note the
wormian bone in the sagittal suture and another
in the left lambdoid suture.
Accessory parietal suture.
Accessory parietal sutures are not exceptional. Of
all the accessory sutures these are the ones that
cause the most confusion.
Accessory parietal sutures may be complete or
incomplete. They may be visualised on the frontal
(arrow) and/or the lateral projections.
References
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we abolish skull Xrays for head injury? Arch Dis
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5. Shapiro R. Anomalous parietal sutures and the
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JC. Craniocerebral trauma in the child abuse
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10. Loder RT, Bookout C. Fracture patterns in battered
children. J Orthop Trauma. 1991;5:428–433.
11. King J, Diefendorf D, Apthorp J, et al. Analysis of 429
fractures in 189 battered children. J Pediatr Orthop.
1988;8:585–589.
12. Rao P, Carty H. Non-accidental injury: review of the
radiology. Clin Radiol. 1999;54:11–24.
4
Adult skull
Anatomy
Normal features on a lateral SXR 48
Towne's view 48
Analysis: false positive diagnoses
Difficulties with interpretation 49
Analysis: recognising a fracture
Linear fracture 50
Depressed fracture 50
Fluid level in the sphenoid sinus 51
A frequent pitfall
Vascular marking versus fracture 52
Following a head injury the imaging examination
of choice is CT1–9.
Plain film skull radiography (SXR) has in the
main been abandoned6 or its use radically
reduced as a first line imaging test both in
children and in adults1–4.
A SXR is now limited to:
▪ where national or local guidelines indicate a
role within a patient management algorithm;
▪ locations where imaging resources are limited
and CT is not available.
If a SXR is obtained there are just three
abnormal features to look for: linear fractures,
depressed fractures, and a fluid level in the
sphenoid sinus.
The standard radiographs
Radiographs comprising a standard SXR series:
▪ A Lateral obtained with a horizontal X-ray
beam, and one additional view depending on the
site of injury.
□ Trauma to the occipital bone
= Towne's view.
□ Any other injury
= PA frontal view.
Abbreviations
CT, computed tomography; PA, posterior-anterior
view; SXR, skull X-ray.
Following an apparently mild head injury requests for
skull radiography (SXR) will occur very infrequently1–9.
Compelling evidence that CT should be the examination of
choice was initially based on a meta-analysis of 20 head
injury surveys7. SXR series may still be requested, perhaps
in remote locations where imaging facilities are limited.
Anatomy
Normal features on a lateral SXR.
Towne's view. This radiograph is obtained
primarily to show the occipital bone. Note that
the frontal and occipital bones are superimposed
on the image. A fracture through the frontal bone
may therefore also be visualised on this
radiograph.
Analysis: false positive diagnoses
Most difficulties with interpretation arise because a normal
appearance can be mistaken for an abnormality. These false
positive diagnoses can be reduced by being familiar with
the following.
▪ The normal sutures and accessory sutures (pp. 36–39).
Specifically, the position and appearance of:
□ the three large sutures: the lambdoid, coronal and
sagittal;
□ the other smaller sutures around the mastoid bones.
▪ The metopic suture (p. 38). The most common accessory
suture persisting in some adults.
▪ Vascular impressions. Specifically:
□ the sites of the most common vessel
grooves/markings;
□ the radiographic features (p. 52) that help to
distinguish between a fracture and a vessel marking.
▪ The normal sphenoid sinus.
□ In young children it is not pneumatised.
□ In adults it contains air. The variable pneumatisation
causes the radiographic appearance to differ widely
between individuals.
Variable
appearance
of
the
normal
sphenoid sinus. Variation occurs in older
children and adults because of individual
differences in pneumatisation.
Analysis: recognising a fracture
In practice, the detection of a SXR abnormality is easy.
There are really only three findings/abnormalities that
indicate that a fracture is present—and one of these is very
rare. The radiographs need to be checked/inspected in a
systematic manner.
Step 1
Scrutinise the area on the radiograph which corresponds to
the site of injury. Vary the windowing if necessary.
Step 2
Look for three abnormalities:
▪ Linear fracture. A lucent (black) line.
▪ Depressed fracture. A dense white area or parallel white
lines due to overlapping or rotated bone fragments.
▪ Fluid level in the sphenoid sinus. This will be visible on
the lateral film since the radiograph is taken using a
horizontal X-ray beam. A fluid level indicates haemorrhage
or cerebrospinal fluid within the sinus and suggests that a
base of skull fracture is present. In practice a sphenoid
sinus fluid level is a rare finding, but it may be the only
abnormality on the radiograph.
Linear fracture.
Fracture through the parietal bone.
Depressed fracture.
Extensive parieto-occipital fracture with both
linear (black) and depressed (white) components.
The appearance of a fluid level in the sphenoid
sinus will depend on the position of the patient. It
is important to know how the patient's lateral
view has been obtained.
Fluid level in the sphenoid sinus in three
different patients. A fluid level indicates a
fracture through the base of the skull.
Each of these radiographs was obtained with
the patient supine and using a horizontal X-ray
beam, as shown in the left hand illustration
above.
A frequent pitfall
Vascular marking versus fracture.
Vascular markings appear grey because the
vessel lies in a groove and consequently only the
inner table of the skull is thinned. Vascular
markings also have branches that gradually
decrease in size as the vessel extends
peripherally. Vessels have well-defined margins
that are white (sclerotic).
In contrast, a fracture will often appear as a
black line, because the inner and outer tables of
the skull have been breached. It may have
branches (ie radiating fracture lines), but these
will not taper in a uniform manner and the
margins of a branch will not be sclerotic.
References
1. [NICE Clinical guideline 56] Head injury: Triage,
assessment, investigation and early management of
head injury in infants, children and adults. 2007.
2. The Royal College of Radiologists. iRefer: Making
the best use of clinical radiology. The Royal College
of Radiologists: London; 2012.
3. [Letter from the Chief Medical Officer, Northern
Ireland] Management of minor head injury in
children. 2005.
4. Reed MJ, Browning JG, Wilkinson AG, Beattie T. Can
we abolish skull Xrays for head injury? Arch Dis
Child. 2005;90:859–864.
5. Stiell IG, Clement CM, Rowe BH, et al. Comparison
of the Canadian CT Head Rule and the New Orleans
Criteria in Patients with Minor Head Injury. JAMA.
2005;294:1511–1518.
6. Glauser J. Head Injury: Which patients need
imaging? Which test is best? Cleveland Clin J Med.
2004;71:353–357.
7. Moseley I. Skull fractures and mild head injury. J
Neurol Neurosurg Psychiatry. 2000;68:403–404.
8. Hofman PA, Nelemans P, Kemerink GJ, Wilmink JT.
Value of radiological diagnosis of skull fracture in
the management of mild head injury: meta-analysis.
J Neurol Neurosurg Psychiatry. 2000;68:416–422.
9. [ISBN 978 1 905813 46 9 May] SIGN Guideline No.
110. Early management of adult patients with a head
injury. Scottish Intercollegiate Guidelines Network.
2009.
5
Face
Normal anatomy: midface & orbit
Facial bone anatomy 54
Occipitomental views 55
Normal anatomy: mandible
The orthopantomogram 56
The temporomandibular joint 56
Straight PA radiograph 57
Analysis: the checklists
Midface injury 58
Suspected blow-out fracture 61
Injury to mandible 61
The common injuries
Injuries to the midface 62
Orbital blow-out fracture 64
Orbital blow-out fracture—the OM findings 66
Injuries to the mandible 68
Pitfalls
Muscle attachment, Black Eyebrow sign, asymmetry
71
The standard radiographs 1 – 9
Midface and Orbit: one or two OM views;
occasionally with a lateral view.
Mandible: OPG, preferably with a PA view.
Regularly overlooked injuries
▪
▪
▪
▪
Tripod fracture.
Blow-out fracture.
TMJ dislocation.
Mandibular condyle fracture.
Abbreviations
CT, computed tomography;
OM, occipitomental view;
OM15/OM30, OM views with 15° or 30° of
angulation of the X-ray beam;
OPG, orthopantomogram;
PA, posterior-anterior;
TMJ, temporomandibular joint.
Normal anatomy: midface & orbit
Facial bone anatomy
Occipitomental (OM) views
Normal anatomy: mandible
The orthopantomogram (OPG)
The OPG is a technique for demonstrating the
mandible, temporomandibular joints and teeth in
a single plane. The X-ray tube and the film
cassette rotate around the patient and the
exposure lasts a few seconds. A panoramic image
is obtained.
The temporomandibular joint
(TMJ)
Straight PA radiograph
Analysis: the checklists
Midface injury
The midface anatomy appears very complex. Try this
approach. Think of the zygoma (malar bone) as a midface
stool with four legs. The seat of the stool is very strong.
The four legs are much weaker, so you need to assess each
leg very carefully.
A five-point checklist
Inspect the OM views as follows:
Concentrate on the stool's legs. For each leg compare the
injured side with the other (normal) side. Look for any
asymmetry or any difference between the appearance of
the matching legs. Check as follows:
1. Leg 1: zygomatic arch.
2. Leg 2: frontal process of the zygoma.
3. Leg 3: orbital floor/rim.
4. Leg 4: lateral wall of the maxillary antrum.
5. Look for fractures and look for:
□ a fluid level (blood from a fracture) in the maxillary
antrum;
□ sinus air in the soft tissues or in the orbit.
Always apply this rule: If any one of the legs is
fractured then always, always, double check whether the
other three legs of the midface stool are intact (see Tripod
fracture, p. 63).
Midface stool—Leg 1
The zygomatic arch. The arch is easy to identify
on the OM view, where it may be likened to an
elephant's trunk. This is a frequent site of
fracture, either as an isolated injury or as part of
a tripod fracture. This radiograph is normal.
Potential pitfall: The normal elephant's trunk
often has a normal developmental bump on its
inferior surface, about half way along the trunk.
Midface stool—Legs 2 & 3
▪ Leg 2: frontal process of zygoma (arrow). The
normal frontozygomatic suture will often be
lucent. Compare this lucency with the uninjured
side.
▪ Leg 3: orbital floor (arrowheads). This leg is
slightly peculiar—it runs backwards and
posteriorly from the rim of the orbit.
Normal radiograph.
Midface stool—Leg 4
Lateral wall of the maxillary antrum (arrow).
Normal radiograph.
Why we do not refer to Le Fort fracture
patterns
Fractures of the middle third of the face are often
classified according to the Le Fort fracture
patterns3,4,10–13. This is a useful classification for
the
maxillofacial
surgeon
when
planning
treatment. However, the Le Fort patterns are not
particularly helpful when carrying out a step-bystep assessment of the plain radiographs in the
Emergency Department. This is because the Le
Fort patterns involve the pterygoid plates and the
precise detail is only reliably provided by a CT
scan with reconstruction of the CT images13.
Designating a precise Le Fort injury pattern (if
present) is at best guesswork when assessing
plain radiographs.
Suspected blow-out fracture
Evaluate the OM view (see p. 66).
Injury to mandible
Evaluate the OPG view (see pp. 68–70).
The common injuries
Casemix varies by hospital type.
Injuries to the midface
Isolated fracture of the zygomatic arch.
This is a common injury (arrow).
Fracture of the inferior orbital margin.
This may occur in isolation or may occur as part
of a tripod fracture. An isolated rim fracture
(arrow) usually involves the inferior and lateral
aspect of this thick, strong, bone.
Tripod fracture. In this combination injury the
cheekbone (ie the zygoma) is detached from its
four points of attachment to the rest of the facial
skeleton3.
A tripod fracture comprises:
▪ fracture through the zygomatic arch (leg 1 of
the four-legged stool)
▪ widening (diastasis) of the zygomaticofrontal
suture (leg 2)
▪ fracture through the inferior orbital rim (leg 3)
▪ fracture through the lateral wall of the
maxillary antrum (leg 4).
Arguably it would be more accurate to call it a quadripod
fracture4,13.
The
Tripod
fracture
is
also
known
as:
Zygomaticomaxillary fracture complex; Zygomaticofacial
fracture; and Trimalar fracture3.
Tripod or quadripod? Terminological discord
The term “tripod fracture” is accepted common usage,
derived from an analogy to a three legged stool to describe
the midface anatomy3,4,14. We agree with Daffner4 that there
are really four legs supporting the stool (the zygoma), so
we evaluate the four legs (pp. 58–59). Some other authors
envisage a three legged stool as follows:
▪ The malar eminence of the zygomatic bone (the cheek
bone) is regarded as the seat of a stool3,4,14.
▪ The three legs are: (1) the zygomatic arch running
backwards; (2) the fronto-zygomatic process running
upwards; (3) the maxillary process running anteriorly and
medially. This third leg is visualised as a somewhat
splayed and hollowed out structure4 forming the floor of
the orbit as well as the lateral wall of the maxillary
antrum.
Orbital blow-out fracture
Following blunt trauma, this injury may be isolated, or
accompany any other major or minor facial injury13. It
results from a direct compressive force to the globe (ie the
eyeball), commonly from a fist, elbow, dashboard, car seat,
or small object such as a squash ball.
The diameter of the object that compresses the eyeball is
invariably greater than the diameter of the eyeball itself.
The blow causes a sudden increase in the intraorbital
pressure behind the eyeball, resulting in a fracture or
fractures of the thin and delicate plates of bone that form
the floor and the medial wall of the orbit.
Approximately 20–40% of patients with an orbital floor
blow-out fracture also have a fracture of the medial wall of
the orbit15.
Clinical impact guidelines
▪ Imaging for a suspected orbital blow-out fracture: only
patients with a clear clinical indication for surgery require
imaging16. Ultrasound evaluation is generally preferable to
radiography.
▪ If some of the orbital contents herniate downwards
through the orbital floor then the inferior rectus muscle
may become tethered. Tethering will result in
diplopia/opthalmoplegia.
▪ Decisions regarding the need for surgery revolve around:
□ muscle entrapment causing opthalmoplegia
□ enopthalmos.
Isolated blow-out fracture.
The blow to the eyeball has increased the
intraorbital pressure and resulted in a fracture of
the thin plate of bone that forms the floor of the
orbit. The soft tissue teardrop in the roof of the
maxillary antrum represents herniated orbital
contents (dark shading). Herniation through the
medial wall of the orbit into the ethmoid sinus
(light shading) commonly occurs but is difficult to
detect on a radiograph.
Orbital blow-out fracture—the OM
findings
▪ The strong inferior orbital margin remains intact when a
blow-out fractureis an isolated injury.
▪ Some orbital contents (fat and/or the inferior rectus
muscle) may herniate downwards through the delicate
orbital floor. This appearance has been likened to an
opaque teardrop hanging from the roof of the maxillary
antrum1. This teardrop may be the only radiographic
evidence of a blow-out fracture.
▪ The bone fragment (from the orbital floor) is very thin
and is rarely seen.
▪ Sometimes a blow-out fracture may be inferred because
air from the breached sinus has entered the orbit. This
orbital emphysema may be positioned above the eyeball.
Air appears black on the radiograph. This has given rise to
the description of the “black eyebrow” sign.
Blow-out fracture with a teardrop. Soft
tissue can be seen hanging from the roof of the
right maxillary antrum.
Blow-out fracture with a black eyebrow.
Note the black eyebrow sign above the left
eyeball. Also note the teardrop in the roof of the
antrum.
Isolated blow-out fractures. All, some or
none of the following may be visible:
(1) Tear drop in antrum.
(2) Fluid level in antrum.
(3) Thin plate of bone from the orbital floor
displaced into the antrum.
(4) Black eyebrow sign.
(5) Opaque (blood filled) ethmoid sinus.
Injuries to the mandible
Assessing the OPG
Sometimes the panoramic view (OPG) fails to show a
fracture17. It is very important that radiological evaluation
of the mandible is correlated with the precise site of
clinical concern. The symphysis is particularly difficult to
evaluate on an OPG; a near normal appearance may occur
when fragments override each other. Clinical suspicion
must always take precedence over a seemingly normal
OPG. If there is any doubt, then additional radiography is
indicated—a PA radiograph in the first instance.
Important points to check
▪ Think of the mandible as a rigid ring of bone. When a ring
of bone is broken it is very common for two fractures to
occur in the ring. 50% of mandible fractures are
bilateral18.
▪ Always check for symmetry—compare one side of the
mandible with the other.
▪ Check for fractures of the body and angle of the
mandible.
▪ Assess the mandibular condyles carefully. Fractures here
may be very subtle.
▪ Check for correct dental occlusion. The upper and lower
teeth should have even and equal spacing on the
radiograph. Displaced fractures, or a fracture through the
neck of a condyle, frequently produce uneven spacing
between the teeth4,11.
▪ Check for any step deformity in the line of the teeth of the
lower jaw. This invariably indicates a fracture.
▪ Assess the temporomandibular joint (TMJ, see p. 56).
Be careful. The OPG will produce some appearances
that can be confused with a fracture. These artefacts are
mainly due to the overlapping image of the pharynx or
tongue. Familiarity with the possible artefacts (pp. 69 and
72) will prevent an incorrect interpretation.
Site incidence of fractures of the mandible.
Note the dislocation of the left TMJ.
OPG.
Two mandible fractures (arrows).
Note: in the OPGs on this page we have
excluded the TMJs for illustrative purposes.
OPG.
Uneven spacing between the upper and lower
teeth suggests a mandible fracture.
OPG.
Step deformity in the line of the lower teeth at
the site of the mandible fracture.
OPG.
Normal, showing artefact due to the tongue
(arrows).
Occasionally an artefact may be misinterpreted
as a fracture.
OPG and PA views.
The OPG does not readily show a fracture, but
the PA does (arrow).
Helpul hint:
If the integrity of the mandible's symphysis
remains equivocal following careful scrutiny of
both the OPG and PA views then an occlusal
radiograph (ie an intraoral image often used in
routine dentistry) will provide excellent detail of
this particular area.
Injuries to the nasal bone
Referral for radiography is not necessary5,6 even if a
fracture is certain on clinical examination. Radiography is
only indicated when requested by a specialist surgeon.
Pitfalls
Normal bump (arrow) on the inferior aspect of
a zygomatic arch. A common normal variant—a
muscular attachment.
Frontal sinus extension into the orbital plate of
the frontal bone (arrow) can mimic the Black
Eyebrow Sign.
Eyelid trapped air (normal) mimicking a black
eyebrow (arrow).
Asymmetry of the normal zygomaticofrontal
sutures on an OM (arrows). This is an occasional
normal variant.
The common artefacts/normal shadows
on an OPG radiograph.
Soft palate (white shaded area). Dorsal surface of
the tongue (black arrows). The oropharyngeal
airway between the soft palate and the dorsal
surface of the tongue creates a black line across
the ramus of the mandible (white arrows). The
band of increased density projected over the
midline is due to the cervical spine which lies
outside the focal plane (black arrowheads). Hyoid
bone (white arrowheads).
References
1. Perry M, Dancey A, Mireskandari K, et al.
Emergency care in facial trauma—a maxillofacial
and ophthalmic perspective. Injury. 2005;36:875–
896.
2. Perry M. Maxillofacial trauma – developments,
innovations and controversies. Injury.
2009;40:1252–1259.
3. Dolan KD, Jacoby CG, Smoker WRK. The radiology
of facial fractures. Radiographics. 1984;4:577–663.
4. Daffner RH. Imaging of facial trauma. Curr Probl
Diagn Radiol. 1997;26:155–184.
5. de Lacey GJ, Wignall BK, Hussain S, Reidy JR. The
radiology of nasal injuries: problems of
interpretation and clinical relevance. Br J Radiol.
1977;50:412–414.
6. Li S, Papsin B, Brown DH. Value of nasal
radiographs in nasal trauma management. J
Otolaryngol. 1996;25:162–164.
7. Raby N, Moore D. Radiography of facial trauma, the
lateral view is not required. Clin Radiol.
1998;53:218–220.
8. McGhee A, Guse J. Radiography for midfacial
trauma: is a single OM15 degrees radiograph as
sensitive as OM15 degrees and OM30 degrees
combined? Br J Radiol. 2000;73:883–885.
9. Pogrel MA, Podlesh SW, Goldman KE. Efficacy of a
single occipitomental radiograph to screen for
midfacial fractures. J Oral Maxillofacial Surg.
2000;58:24–26.
10. Walton RL, Hagan KF, Parry SH, et al. Maxillofacial
trauma. Surg Clin North Am. 1982;62:73–96.
11. The Face. Chan O. ABC of Emergency Radiology.
3rd ed. Willey Blackwell; 2013.
12. Salvolini U. Traumatic injuries: imaging of facial
injuries. Eur Radiol. 2002;12:1253–1261.
13. Hopper RA, Salemy S, Sze RW. Diagnosis of Midface
Fractures with CT: What the Surgeon needs to know.
RadioGraphics. 2006;26:783–793.
14. Rutherford WH, Illingworth R, Marsden AK, et al.
Accident and Emergency Medicine. 2nd Ed.
Churchill Livingstone: Edinburgh; 1989.
15. Dolan KD, Jacoby CG. Facial fractures. Semin
Roentgenol. 1978;13:37–51.
16. Bhattacharya J, Moseley IF, Fells P. The role of plain
radiography in the management of suspected orbital
blow-out fractures. Brit J Radiol. 1997;70:29–33.
17. Druelinger L, Guenther M, Marchand EG.
Radiographic evaluation of the facial complex.
Emerg Med Clin North Am. 2000;18:393–410.
18. Pathria MN, Blaser SI. Diagnostic imaging of
craniofacial fractures. Rad Clin North Am.
1989;27:839–853.
6
Shoulder
Normal anatomy
AP view; apical oblique view; lateral scapula view—ie
the Y view 75–77
Analysing the radiographs
The AP radiograph; apical oblique view 78–79
The common fractures
Greater tuberosity of the humerus 80
Humeral head and/or rim of the glenoid 80
Clavicle 81
The common dislocations
Anterior dislocation of the GH joint 82
Anterior dislocation of the GH joint with
accompanying fractures 84
Subluxation and dislocations at the ACJ 86
Uncommon but important injuries
Posterior dislocation at the GH joint 88
Fractures of the proximal humerus 90
Fractures of the body or neck of the scapula 91
Sternoclavicular rupture 91
Inferior dislocation of the humeral head (luxatio
erecta) 91
Pitfalls
Positioning, ACJ assessment, developmental variants
that can mislead 92
Regularly overlooked injuries
▪ Dislocations/subluxations: ACJ subluxation;
complete rupture of the CC ligaments; posterior
dislocation of humeral head.
▪ Fractures: scapula blade; glenoid rim or
humeral head as a complication of an anterior
dislocation at the GH joint.
The standard radiographs
AP view and a second view (see p. 74).
Abbreviations
ACJ, acromioclavicular joint;
AP, anterior-posterior;
CC, coracoclavicular;
GH, glenohumeral;
SC, sternoclavicular;
Y projection (view), scapula “Y” lateral.
Standard radiographs
Shoulder injury:
▪ The AP view is standard in all departments.
▪ The precise second view will vary.
□ We prefer the apical oblique projection (aka Modified
Trauma Axial, MTA; see p. 76), because it allows
gentle positioning of the patient, provides excellent
demonstration of dislocations and shows fractures
extremely well1,2.
□ Second best: the scapula Y lateral (see p. 77). The
patient is comfortable as the arm is not moved, and a
true scapula Y lateral will show posterior dislocations3.
But this view must be technically very precise, and
fractures can be difficult to identify.
□ The axial (armpit) view is not recommended. It will
show a posterior dislocation and most fracture
fragments, but it requires abduction of the injured arm
which can be very painful. It can also cause further
damage. Frequently it results in a poor radiograph.
Suspected fracture of the clavicle:
▪ Common practice: a single AP view.
▪ Some departments add an additional AP with the beam
angled 15° upwards.
Note our descriptive emphasis in this chapter
We are strong advocates that the second view for an
injured shoulder should be the apical oblique radiograph
rather than any alternative second view. Consequently, our
descriptions concentrate mainly on the AP view and the
apical oblique view of the injured shoulder.
Normal anatomy
AP view
The normal humeral head does not appear round
and symmetrical. Its shape mimics the head of an
old fashioned walking stick. This is due to the
radiographer positioning the humerus in external
rotation.
The articular surfaces of the glenoid and the
humerus parallel one another.
The inferior cortex of the lateral part of the
clavicle aligns with the inferior cortex of the
acromion process. There is no step between these
cortices.
Apical oblique view1,2
The normal GH joint.
▪ A line drawn through the apex and the centre of
the base of the (imaginary) cone should pass
through the centre of the humeral head.
▪ On this projection, anterior is downwards and
posterior is upwards, as shown in the top right
drawing.
Lateral scapula view—ie the Y view3
The humeral head overlies the centre of the
glenoid. The Y is formed by the junction of the
scapular blade, the coracoid and the spine of the
scapula. On this view anterior is towards the ribs
and posterior is away from the ribs.
Analysis: the checklists
The AP radiograph
Ask yourself five questions.
1. Is the humeral head lying directly below the coracoid
process?
Yes = anterior dislocation.
2. Does the humeral head have a walking stick shape, and
does its articular surface parallel the glenoid margin?
No = use the second view to rule out a posterior
dislocation.
3. Is the acromioclavicular joint normal—ie do the inferior
cortices of the clavicle and acromion process align?
No = subluxation or dislocation at the acromioclavicular
joint.
4. Is the coracoclavicular distance more than 1.3 cm?
Yes = stretching or rupture of the coracoclavicular
ligaments (see p. 86).
5. Is there a fracture of the head or neck of the humerus,
the glenoid margin, the clavicle, the body or neck of the
scapula, or a rib fracture?
Normal shoulder.
Apply the five questions to this radiograph.
Apical oblique view1,2
Ask yourself three questions.
1. Do the articular surfaces of humerus and glenoid lie
immediately adjacent to each other—ie does the centre
of the triangle base line up with the centre of the glenoid
articular surface?
No = a glenohumeral joint dislocation or subluxation.
2. Is there a fracture of the head or the neck of the
humerus?
3. Is there a fracture of the glenoid margin?
The apical oblique view is excellent in
demonstrating a posterior dislocation at the
glenohumeral joint.
This radiograph shows a posterior dislocation.
The two drawings illustrate how an inexperienced
observer can readily detect the abnormal
alignment on the radiograph.
See p. 76 for the expected normal alignment on
an apical oblique view.
The common fractures4–9
Greater tuberosity of the humerus
Often undisplaced and is then very subtle
(arrow). Examine the AP view very carefully.
Occasionally these fractures are invisible on the
plain radiographs.
Humeral head and/or rim of the
glenoid
A recognised
dislocation.
complication
of
an
anterior
This apical oblique view shows the abnormal
articular surface of the humeral head with a
fragment (arrowhead) adjacent to it; a defect in
the rim of the glenoid is also present (arrow). The
glenohumeral articulation is normal.
Clavicle
Accounts for 35% of all fractures involving the shoulder
region6.
▪ Fractures of the mid third account for 85% of clavicular
fractures. Most of these occur in patients less than 20
years old. Lateral third fractures occur less frequently, and
mainly in adults.
▪ In young children, a Greenstick fracture may occur (pp.
18–19), and appears as a slight kink in the bone.
▪ Clinical impact guideline: a clavicle fracture in an
infant is a recognised complication of traumatic birth
delivery; be careful not to misdiagnose this finding as a
non-accidental injury.
Fracture of the middlethird of the
clavicle.
Most mid third fractures occur as a result of a fall
on the shoulder. Some result from a transmitted
force (ie a fall on the outstretched hand).
Fracture of the lateral third of the
clavicle.
Often due to a direct blow to the clavicle (eg
during a contact sport, a fall, or a road traffic
accident).
Clinical impact guideline: more likely than a
middle third fracture to be associated with
delayed union or non union10.
The common dislocations4,8,9
Anterior dislocation of the
glenohumeral (GH) joint
GH dislocations are the commonest traumatic dislocations
of the skeleton. Anterior dislocations represent 95% of all
GH dislocations. The appearances shown here are
characteristic and on the whole the diagnosis is
straightforward.
Anterior GH dislocations are often accompanied by
fractures of the greater tuberosity of the humerus: see p.
80.
Anterior dislocation of GH joint: AP
view.
The head of the humerus is displaced medially
(towards the ribs). In the majority of cases it lies
below the coracoid process.
Essential: The second view needs to be
scrutinised for:
▪ confirmation
▪ fractures
▪ detached fragments.
Anterior dislocation of GH joint: Apical
oblique view.
The head of the humerus is seen well away from
the glenoid articular surface and positioned
anteriorly.
When you draw in the glenoid cone or triangle
(see p. 76), the line passing through the apex of
the triangle does not pass through the centre of
the head of the humerus.
A bonus from an apical oblique view: exquisite
visualisation of bones and articular surfaces.
Anterior dislocation of GH joint: Scapula
Y view.
The humeral head (arrows) does not cover the
glenoid (arrowheads). The glenoid is identified as
being at the junction of the three limbs of the “Y”
(see p. 77).
A disadvantage of the scapula Y: fractures are
often not visible.
Pitfall: Haemorrhage causing
subluxation.
Following an injury, usually with an intra-articular
fracture, there may be extensive haemorrhage
into the joint. The increase in fluid volume may
push the head of the humerus inferiorly (as
shown),
but
not
medially.
This
inferior
displacement can be misinterpreted as a
dislocation.
The haemorrhage will absorb within a week or
two and consequently the subluxation will
resolve.
Pitfall: Hemiplegia and a subluxed
humeral head
In a patient with hemiplegia, the humeral head on
the affected side might not be maintained in a
normal position by good muscle tone. It can drop
inferiorly because the deltoid muscle is
paralysed. This inferior subluxation is permanent.
Anterior dislocation of the
glenohumeral (GH) joint with
accompanying fractures
A fracture of the greater tuberosity of the humerus
frequently accompanies a dislocation.
▪ Always scrutinise both shoulder views for a fragment
detached from the glenoid rim or from the posterior and
superior aspect of the head of the humerus. If a fragment
enters the joint it may prevent a successful reduction.
▪ Compression injuries also occur: Hill–Sachs deformity
and Bankart's lesion (see opposite).
Patient (left) with a fracture of the greater
tuberosity and an anterior dislocation on this
apical oblique view. Patient (right) with an
anterior dislocation and a fragment (arrow)
detached from the head of the humerus
(arrowheads).
A previous anterior dislocation had caused a
fracture of the inferior margin of the glenoid
(arrow).
Clinical impact guideline. The post reduction
radiograph must be checked to ensure that any
accompanying fracture has reduced. If a
fragment remains displaced it may require open
reduction and internal fixation.
Hill–Sachs deformity.
A
compression
fracture
(arrow)
of
the
posterolateral aspect of the humeral head.
This injury results from impaction of the
humeral head against the glenoid margin. It
occurs in as many as 50% of anterior
dislocations7.
Bankart's lesion.
A fracture of the anterior lip of the glenoid.
It results from impaction by the humeral head
on the glenoid during dislocation.
This apical oblique radiograph was taken
following a successful reduction. The glenoid
fragment is well shown inferiorly (arrow).
Subluxations and dislocations at the
acromioclavicular joint (ACJ)
This joint is the sole bone to bone attachment of the upper
limb to the rest of the skeleton.
Assess this joint on the AP view only. The other
projections may mislead.
The ligaments
The coracoclavicular (CC) ligaments attach the
patient's arm to the body, and prevent vertical
movement of the clavicle and ACJ. The normal
distance between the coracoid and clavicle on the
AP view is usually less than 1.3 cm4,5. Complete
dislocation of the ACJ indicates rupture of CC
ligaments (see opposite).
Abnormal findings:
▪ The inferior cortices of the clavicle and
acromion do not align.
▪ If the CC distance is greater than 1.3 cm then
rupture of the CC ligaments is probable.
Stress radiographs will help in equivocal cases
of CC ligament rupture. The radiograph should
ideally be obtained with the weights hanging
from the wrists, in order to ensure full relaxation
of the upper limb muscles.
Weight bearing views.
Normal and abnormal alignment of the inferior
surfaces of the acromion process and the clavicle.
(a) is normal;
(b) ACJ dislocation.
Grading the injuries to the ligaments11.
Grade I: Stretching or partial rupture of ACJ
ligament, but intact CC ligaments. Radiological
findings: normal, or slight step at ACJ.
Grade II: Rupture of ACJ ligament and
stretching of CC ligaments. Radiological findings:
a step at the ACJ. May need stress views if
equivocal.
Grade III: Rupture of ACJ ligament and
rupture of CC ligaments. Radiological findings: a
step at the ACJ and increased CC distance (ie
greater than 1.3 cm). May need stress views to
show the full extent of the damage.
Clinical impact guidelines.
ACJ subluxation (left) is invariably treated
conservatively, usually with an excellent outcome.
On the other hand, a complete ACJ dislocation
(right) is an important injury. Opinion regarding
management
varies.
It
will
be
treated
conservatively by some surgeons who then
reserve surgery for those who develop persistent
symptoms. Other surgeons advise early surgery
for nearly all ACJ dislocations, particularly for
manual workers and athletes.
Uncommon but important injuries
Posterior dislocation at the
glenohumeral (GH) joint
The naming of this injury is arguably inaccurate. It is very
rarely a complete dislocation. Despite the notable posterior
displacement it is, invariably, a major subluxation.
On many occasions there will be an accompanying
fracture of the anterior aspect of the humeral head.
Uncommon. Fewer than 5% of shoulder dislocations. As
many as 50% are overlooked even when initial radiographs
show the abnormality7.
Often caused by violent muscle contraction; either during
a convulsion or from an electric shock. Sometimes, both
shoulders will dislocate simultaneously8.
Posterior dislocation: characteristic
appearances on the AP view.
The rotated and posteriorly displaced humeral
head loses the normal parallelism of the articular
surfaces, as in the two posterior dislocations
below.
The humeral head frequently appears rounded
—no longer the contour of an old fashioned
walking stick. The globular contour has been
likened to a light bulb or drumstick appearance
(right).
Posterior dislocation: characteristic
appearances on an apical oblique view.
The main mass of the humeral head lies posterior
to the glenoid.
Posterior dislocation: characteristic
appearance on a scapula Y view7.
The centre of the humeral head lies posterior to
the junction of the three limbs of the Y (ie away
from the ribs).
Fractures of the proximal humerus
Neck of humerus
Usually occurs in an osteoporotic elderly patient
as a result of a fall. A greater tuberosity fracture
may also be present.
In younger patients it is invariably caused by a
violent force.
In children and adolescents the growth plate is
involved (Salter–Harris fracture, p. 15).
Elderly patient. Impacted fracture of the neck of
the humerus.
A large joint effusion (haemorrhage) has caused
the head of the humerus to sublux inferiorly.
Clinical impact guidelines for fractures
of the proximal humerus.
In elderly patients an impacted fracture need not
be immobilised and a sling is utilised with
physiotherapy and active shoulder movements.
Unimpacted fractures are frequently managed
with sling immobilisation.
Younger patients will usually require fracture
reduction if the fragments are displaced.
Sometimes a closed reduction, sometimes open
reduction and internal fixation8,9.
Fractures of the body or neck of the
scapula
Usually result from a high impact event. Serious soft tissue
or neurovascular injuries are recognised associations8.
You will only see what you look for…these fractures are
easy to overlook. Always check the AP and the second view
very carefully.
Road traffic accident. Transverse fracture
through the body of the scapula (arrows).
Sternoclavicular rupture
Consequent on a high impact injury. Very, very, rare. An
associated vascular injury occurs in 25% of cases4,5.
Inferior dislocation of the humeral
head (luxatio erecta)
Very rare and accounts for less than 0.5% of all shoulder
dislocations. The clinical finding is classical—a Statue of
Liberty appearance with the arm elevated and the forearm
fixed and resting on the head5,12. The AP radiograph shows
the head of the humerus nestling immediately inferior to
the glenoid with the humerus pointing upwards. Usual
cause: forceful hyperabduction of an abducted limb.
Pitfalls
Positioning
The effect of internal rotation on the contour of
the humeral head. Standard AP radiographs are
always obtained with the humerus positioned in
slight external rotation and this accounts for the
humeral head looking like a club-headed walking
stick as shown in (a). However, the injured joint
may be so painful that the patient holds the arm
in internal rotation. When this occurs then a light
bulb appearance (b,c) may result and can mimic a
posterior dislocation. An error in interpretation
will be avoided by checking the precise position
of the humerus on the second view.
ACJ assessment
Be careful: Do not evaluate the integrity of the
acromioclavicular joint (ACJ) on any of the second
views. The appearance of the ACJ can be very
deceptive on these projections. Always assess the
ACJ on the AP radiograph alone.
Developmental variants that can
mislead
On the AP view in the immature skeleton, the
growth plate for the humeral head lies obliquely,
appearing as two separate lines. Either of these
normal lines (arrows) may be mistaken for an
undisplaced fracture.
The tips of the acromion and coracoid
processes ossify from separate ossification
centres. In children these secondary centres may
be mistaken for fracture fragments.
Occasionally the secondary centre at the tip of
the acromion does not fuse with the rest of the
scapula, and remains as a separate bone—the os
acromiale. It may be mistaken for a fracture.
Interestingly, when present, this accessory ossicle
is usually bilateral.
The medial clavicular epiphysis is one of the
last of all the secondary centres to unite to the
parent bone (at approximately 25 years of age).
Do not confuse this epiphysis (arrow) with a
fracture.
The rhomboid fossa.
A common normal variant. This notch or
prominent depression in the inferior aspect of the
medial portion of the clavicle is the point of
insertion
of
the
costoclavicular
ligament
attaching the clavicle to the costal cartilage of
the first rib.
Do not mistake it for a pathological erosion of
the clavicle.
Cystic appearance: the superior and lateral
aspect of the head of a normal humerus will
sometimes appear lucent on a radiograph. A cyst
or an area of destruction may be diagnosed
erroneously.
References
1. Kornguth PJ, Salazar AM. The apical oblique view of
the shoulder: its usefulness in acute trauma. Am J
Roentgenol. 1987;149:113–116.
2. Garth WP, Slappey CE, Ochs CW. Roentgenographic
demonstration of instability of the shoulder: the
apical oblique projection. J Bone Joint Surg.
1984;66:1450–1453.
3. Horsfield D, Jones SN. A useful projection in
radiography of the shoulder. J Bone Joint Surg.
1987;69B:338.
4. Rogers LF. Radiology of skeletal trauma. 3rd ed.
Churchill Livingstone; 2001.
5. Neustadter LM, Weiss MJ. Trauma to the shoulder
girdle. Semin Roentgenol. 1991;26:331–343.
6. Nordqvist A, Petersson CJ. Incidence and causes of
shoulder girdle injuries in an urban population. J
Shoulder Elbow Surg. 1995;4:107–112.
7. The Shoulder. Chan O. ABC of Emergency Radiolgy.
3rd ed. Wiley Blackwell; 2013.
8. Hamblen DL, Simpson AH. Adams's Outline of
Fractures including Joint Injuries. 12th ed. Churchill
Livingstone; 2007.
9. Solomon L, Warwick DJ, Nayagam S. Apley's
Concise System of Orthopaedics and Fractures. 3rd
ed. Hodder Arnold; 2005.
10. Edwards DJ, Kavanagh TG, Flannery MC. Fractures
of the distal clavicle; a case for fixation. Injury.
1992;23:44–46.
11. Mlasowsky B, Brenner P, Duben W, et al. Repair of
complete acromioclavicular dislocation (Tossy Stage
III) using Balser's hook plate combined with
ligament sutures. Injury. 1988;19:227–232.
12. Patel DN, Zuckerman JD, Egol KA. Luxatio erecta:
case series with review of diagnostic and
management principles. Am J Orthop. 2011;40:566–
570.
7
Paediatric elbow
Normal anatomy
AP view; lateral view 96
Elbow fat pads 97
The CRITOL sequence 98
Medial epicondyle 100
Two anatomical lines 101
Analysis: four questions to answer
Are the fat pads normal? 102
Is the anterior humeral line normal? 103
Is the radiocapitellar line normal? 104
Are the ossification centres normal? 105
The common injuries
Supracondylar fracture 106
Fracture of the lateral humeral condyle 109
Avulsion of the medial epicondyle 110
Rare but important injuries
Avulsion of the lateral epicondyle, Dislocation of the
head of the radius, Monteggia injury 112
Pitfalls
Normal variants than can mislead 113
Normal appearance of the epicondyles 114
Misleading lines 114
Regularly overlooked injuries
▪ Undisplaced supracondylar fracture.
▪ Fracture, lateral condyle of humerus.
▪ Monteggia injury1,2.
The standard radiographs
AP in full extension.
Lateral with 90 degrees of flexion.
Abbreviations
CRITOL: Capitellum, Radial head,
epicondyle,
Trochlea,
Olecranon,
epicondyle.
Internal
Lateral
Anatomy
AP view—child age 9 or 10 years
Lateral view—child age 9 or 10 years
Elbow fat pads
There are pads of fat close to the distal humerus, anteriorly
and posteriorly. They are extrasynovial but intracapsular.
▪ Look for the fat pads on the lateral. They are not seen on
the AP view.
▪ The fat is visualised as a dark streak amongst the
surrounding grey soft tissues.
▪ The anterior fat pad is seen in most (but not all) normal
elbows. It is closely applied to the humerus, as shown
below.
▪ The posterior fat pad is not visible on a normal
radiograph because it is situated deep within the
olecranon fossa and hidden by the overlying bone.
AP and lateral: the CRITOL sequence
CRITOL: the sequence in which the ossified
centres appear
At birth the ends of the radius, ulna and humerus are lumps
of cartilage, and not visible on a radiograph. The large,
seemingly empty, cartilage filled gap between the distal
humerus and the radius and the ulna is normal.
From 6 months to 12 years the cartilaginous secondary
centres begin to ossify. There are six ossification centres.
Four belong to the humerus, one to the radius, and one to
the ulna. Gradually the humeral centres ossify, enlarge, and
coalesce. Eventually each of the fully ossified epiphyses
fuses to the shaft of its particular bone.
When the ossification centres appear is not
important. The order is important.
Normal ossification centres in the cartilaginous
ends of the long bones.
Order of appearance from birth to 12 years:
C = capitellum
R = radial head
I = internal epicondyle
T = trochlea
O = olecranon
L = lateral epicondyle
Normal appearances are shown opposite.
Exceptions to the CRITOL sequence?
Exceptions are an occasional normal variant3,4.
A 2011 survey4 of 500 paediatric elbow radiographs
found:
▪ 97% followed the CRITOL order.
▪ 3% showed a slightly different order.
▪ But: there were no instances in which the trochlear
ossification centre appeared before the medial (internal)
epicondylar centre.
Conclusions
▪ CRITOL is a really helpful tool when analysing a child's
injured elbow.
▪ Occasionally a minor variation in the sequence may occur.
▪ Use the rule: “I always appears before T”. So, if you see
the ossified T before the I then the internal epicondyle has
almost certainly been avulsed and is lying within the
joint… ie it is masquerading as the trochlear ossification
centre (see p. 105).
Capitellum
Radial head
Internal (ie medial) epicondyle
Trochlea
Olecranon
Lateral epicondyle
Medial epicondyle—normal anatomy
Is the medial epicondyle slightly displaced/avulsed? A
common dilemma.
▪ The rule to apply:
On the AP radiograph a normally positioned epicondyle
will be partly covered by some of the humeral metaphysis.
▪ A caveat:
Occasionally a child in pain will hold the forearm in a
position of slight internal rotation. Rotation will project
the metaphysis of the humerus away from a normally
positioned epicondyle.
▪ Conclusions:
When checking the position of the internal epicondyle on
the AP radiograph:
1. If part of the epicondyle is covered by part of the
humeral metaphysis then an avulsion has not
occurred.
2. A completely uncovered epicondyle indicates an
avulsion… unless the forearm bones are slightly
rotated.
Clinical impact guidelines: the I in
CRITOL
The ossification centre for the internal (ie medial)
epicondyle is the point of attachment of the
forearm
flexor
muscles.
Vigorous
muscle
contraction may avulse this centre (see p. 105).
The most common injury mechanism is a fall on
an outstretched hand. Avulsions also occur in
children who are involved in throwing sports,
hence the term “little leaguer's elbow”.
When a major displacement of the internal
epicondyle occurs the bone can become trapped
within the elbow joint. This is a well recognised
complication of a dislocated elbow, occurring in
50% of cases following an elbow subluxation or
dislocation. A major avulsion is easy to overlook
when an elbow has been transiently dislocated
and then reduces spontaneously5,6 because the
detached epicondyle may, on the AP radiograph,
be mistaken for the normally positioned trochlear
ossification centre (p. 105).
I before T. Though the CRITOL sequence may
vary slightly there is a constant: the trochlear (T)
centre always ossifies after the internal
epicondyle. Therefore apply this rule: if the
trochlear centre (T) is visible then there must be
an ossified internal epicondyle (I) visible
somewhere on the radiograph. If the internal
epicondyle is not seen in its normal position then
suspect that it is trapped within the joint.
AP and lateral—two anatomical lines
Anterior humeral line (on lateral).
Normal alignment: when drawn along the
anterior cortex of the humerus, in most normal
patients at least one third of the ossifying
capitellum lies anterior to this line.
Be careful: in very young children the
ossification within the cartilage of the capitellum
might be minimal (ie normal and age related),
and so is insufficiently calcified and does not
allow application of the above rule.
This line helps you to detect a supracondylar
fracture with posterior displacement (pp. 106–
108).
Radiocapitellar line (on AP and lateral)
Normal alignment: On the lateral radiograph a
line drawn along the central axis of the proximal
2–3 cm of the radius should pass through the
centre of the capitellum. If it fails to do so, the
radius is dislocated at the elbow joint. The same
inference can be applied to the AP view but less
reliably7.
Analysis: four questions to answer
Question 1—Are the fat pads
normal?
Check the fat pads on the lateral projection.
If an effusion is present it distends the capsule,
displacing the fat pads away from the bone. This provides
evidence of a significant injury.
▪ A displaced anterior fat pad (the sail sign) is abnormal8.
▪ A visible posterior fat pad is always abnormal1. It denotes
a very large effusion—usually a considerable volume of
blood in the joint.
▪ Not all joint effusions are associated with a fracture8.
▪ An effusion indicates that a significant injury has
occurred, even if a fracture is not seen. Whenever either
fat pad is displaced but no fracture identified, the arm
needs to be placed in a collar and cuff until orthopaedic
assessment a few days later. Some of these patients will
have sustained an undisplaced fracture8,9.
▪ NB: Absence of a visible fat pad does not exclude a
fracture. The radial neck is usually extracapsular, and a
fracture of the neck may not produce a joint
effusion/haemarthrosis or displace the fat pads.
Alternatively, if the joint capsule has ruptured, blood
gradually leaks out of the joint into the surrounding soft
tissues.
Clinical impact guidelines: Fat pad
displacement, but no fracture or dislocation
identified — what to do?
It is most important that neither an undisplaced
supracondylar fracture nor a displaced internal epicondyle
are overlooked. The radiographs must be checked by an
experienced observer before the patient is discharged.
If a fracture is still not identified then manage as for an
undisplaced fracture. At clinical review in 10 days: if
clinically normal—no further radiography; if clinically
abnormal—obtain repeat radiographs.
The anterior and posterior fat pads (ie the black
streaks on the radiograph) are displaced by a
large effusion in the elbow joint.
Question 2—Is the anterior humeral
line normal?
The supracondylar region is a site of particular weakness in
the developing humerus. There is a deep posterior fossa
above the humeral condyles, which allows the olecranon to
lie within it when the forearm is fully extended. Thus the
humerus has a narrow AP diameter at this level and is a
point of weakness.
The rule: A line traced along the anterior cortex of the
humerus should have at least one third of the capitellum
anterior to it (see p. 101).
▪ If less than one third of the capitellum lies anterior to this
line, there is a strong probability of a supracondylar
fracture with the distal fragment (including the
capitellum) displaced posteriorly (see p. 107).
The drawing:
The capitellum is of a good size. Approximately a
third of it lies in front of the anterior humeral
line. Normal appearance.
The radiographs:
The abnormal anterior humeral line suggests a
supracondylar fracture.
Question 3—Is the radiocapitellar
(RC) line normal?
The rule: A line drawn along the longitudinal axis of the
radial head and neck should pass through the capitellum. If
it does not pass through the capitellum: a radial head
dislocation is likely.
▪ Be careful: the normal radius frequently shows a bend
or slight angulation in the region of its tuberosity. Draw
the RC line along the long axis of the proximal 2–3 cm of
the radius…not along the long central axis of the shaft of
the radius.
▪ Be careful: this rule is always valid on a true lateral7,
but on the AP radiograph the RC line can be distorted by
radiographic positioning. A misleading RC line on the AP
view may also be due to eccentric ossification of either the
radial head or the capitellar epiphysis, which can cause
the RC line to be directed away from the capitellum.
▪ Be very careful: Monteggia injury1,2. Whenever there is
a fracture of the shaft of the ulna, evaluate the RC line
carefully, because there may be an associated dislocation
of the radial head. Particularly likely when there is
angulation or displacement of the fracture but the radial
shaft appears intact (see pp. 112–113).
The drawing shows an elbow with a normal RC
line.
The radiograph shows that a RC line would not
pass through the capitellum.
Diagnosis: the radial head is dislocated.
Question 4—Are the ossification
centres normal?
A most important question. Normal appearances are
described on pp 96–99.
Check:
▪ The position of the medial epicondyle.
▪ The appearance of the lateral epicondyle.
▪ The CRITOL ossification sequence.
Avulsion of the internal (medial) epicondyle. 1
= normal; 2 = slight avulsion; 3 = major avulsion;
4 = major avulsion and the epicondyle lies within
the joint.
Two different patients. Both had fallen on an
outstretched hand. Patient (a): normal position of
the internal epicondyle. Note that the metaphysis
of the humerus overlaps part of the epicondyle.
Patient (b): the internal epicondyle has been
avulsed. Note the lack of metaphyseal overlap.
The common injuries
Supracondylar fracture
60% of elbow fractures9–12. The commonest fracture in
children under the age of 7 years, and the second
commonest up to the age of 16 years9.
Caused by falling on an outstretched hand with
hyperextension of the elbow. The supracondylar bone is
relatively thin and weak in a child.
25% of these fractures are minimally displaced or
undisplaced11,12. Displacement is usually posterior due to
the direction of the fall. Very occasionally the displacement
is anterior, resulting from a blow to the posterior aspect of
the elbow.
Assessment of the anterior humeral line (p. 101) is the
key to recognising any posterior displacement of this
fracture.
Be cautious:
▪ The anterior humeral line rule is not always reliable in
very young children, due to normal but partial ossification
of the capitellum.
▪ If the anterior humeral line appears abnormal and a
supracondylar fracture is not identified, seek an
experienced opinion.
Clinical impact guideline:
This fracture may cause vascular damage if there is major
displacement. The brachial artery is situated anterior to the
humeral cortex in the supracondylar region of the humerus,
and can be lacerated by a bone fragment.
▪ If this fracture is displaced it needs to be reduced and
stabilised to protect the vascular supply to the arm12.
▪ Bleeding from torn vessels can also cause a compartment
syndrome; ie bleeding or swelling within the adjacent
muscles that are enclosed by a tight fascia. The pressure
within the compartment can rise and this can cut off the
blood supply to the muscles.
This child has fallen on his outstretched hand
and sustained a supracondylar fracture—the bone
has snapped across this thin part of the humerus.
The posterior displacement has occurred partly
because of the resulting pull of the triceps muscle
on the olecranon.
Supracondylar
displacement.
Very common.
fracture
with
Undisplaced supracondylar fracture.
Common.
posterior
Supracondylar
displacement.
Uncommon.
fracture
with
anterior
Abnormal anterior humeral line. Supracondylar
fracture with posterior displacement.
Abnormal anterior humeral line. Supracondylar
fracture with posterior displacement.
Normal elbow. The anterior humeral line is
normal. Incidentally, the medial epicondyle is
positioned far posteriorly. This is the normal
position.
Abnormal anterior humeral line. Supracondylar
fracture with posterior displacement.
Normal anterior humeral line. Note
undisplaced supracondylar fracture (arrow).
the
Abnormal anterior humeral line. Supracondylar
fracture with posterior displacement.
Fracture of the lateral humeral
condyle
The commonest fracture in children under the age of seven
years. In many cases the fracture involves only the
cartilaginous part of the distal humeral epiphysis. Cartilage
does not show up on a radiograph. Consequently, the
extensive epiphyseal component of this fracture is often not
fully appreciated. In effect this is a Salter–Harris type 4
epiphyseal fracture (see p. 15).
▪ Precise reduction is important If the fracture is displaced.
Otherwise stiffness, cubitus valgus and / or a delayed
ulnar nerve palsy may result13.
▪ Helpful hint: there is a recognised association between
olecranon fractures and lateral condyle fractures. Have
you checked the olecranon?
The drawings above show the full extent of the
fracture through the invisible cartilage of the
condyle: (a) undisplaced fracture; (b) displaced
fracture.
The radiograph shows a fracture through the
lateral humeral condyle. However, its full extent
through the cartilage is not / will not be visible.
Avulsion of the medial epicondyle
Results from a pull at the insertion of the common origins
of the flexor muscles, usually as a result of a valgus stress
during a fall on the outstretched hand. May also occur in
throwing sports such as baseball pitching (“little leaguer's
elbow”).
Minor avulsion is common. The avulsed ossification
centre will usually heal by fibrous union and the
attachment of the flexor muscles will be stable5,6,13. Surgical
reduction is often indicated when the avulsion is extensive,
in order to obtain and preserve full function.
Mild/minor displacement.
Extensive displacement.
The avulsed epicondyle is situated within the
elbow joint.
Normal position of medial epicondyle. Note the
partial overlap of the epicondyle by the
metaphysis of the humerus (p. 100). The other
secondary centres are also normal.
Pulled (“nursemaids”) elbow
Usually occurs between the age of one and four years.
Caused by a sudden jerk on the arm, often when
restraining a child who is charging off to cross a busy road,
or when being playfully swung around by the arm. The jerk
causes the annular ligament around the head of the radius
to stretch and consequently the radial head subluxes or
slips very slightly.
Clinical findings are classical: the arm is held in flexion
and pronation. Reduction is usually simple, quick and
effective.
Radiography is not indicated as the history and clinical
findings are characteristic. Also, the radiographs will
always appear normal.
Nursemaid's elbow.
A widely held misconception is that the head of
the radius subluxes distally under the annular
ligament (a,b).
An ultrasound study14 provides a different
explanation (c). A cross-section at the level of the
annular ligament demonstrates a shallow
depression on the lateral margin of the ulna (1).
The normal anatomy is shown in (2). A pulled
elbow injury causes the head of the radius to
perch on the anterior rim of the ulnar depression
(3). This ventral subluxation explains why a
successful reduction is often preceded by a snap
or a click, caused by the head dropping back into
its natural position.
Plastic bowing injury
In children the long bones are relatively pliable as
compared with an adult and there may not be the usual
ulnar or radial fracture with a visible break2,11. Instead, a
forearm bone may bend. This is referred to as a plastic
bowing injury or fracture (p. 21).
Rare but important injuries
Avulsion of the lateral epicondyle
A very rare injury. The normal elbow will often show the
lateral epicondyle well away from the adjacent humeral
metaphysis. This is not a cause for worry if the two
adjacent cortices parallel one another (as shown on p. 113).
Isolated dislocation of the head of
the radius
Abnormal radiocapitellar (RC) line (p.
Isolated dislocation of the radial head.
101).
Monteggia injury
A Monteggia injury adheres to the principle of the Two
Bone Rule. In a two bone system15 such as the radius and
ulna, where the bones are tightly bound together, they can
be regarded as acting as a single functional unit. If one of
the bones is fractured and displaced (or bent in a child)
then there will need to be an additional disturbance in their
relationship, often a displaced fracture of the adjacent
bone. If the adjacent bone is intact then the disturbance
will affect a joint. A Monteggia injury comprises a displaced
fracture of the ulna (or a bowed ulna), an intact radial
shaft, and a dislocated head of the radius.
Fracture of middle third of the ulna with slight
angulation. But… the RC line is abnormal. This is
a Monteggia injury.
Top: displaced fracture of the ulna. Intact radius.
RC line is abnormal indicating a dislocation of the
head of the radius.
Bottom: the shaft of the ulna is bent. Radial
shaft is intact. RC line is abnormal.
In both cases these are Monteggia injuries.
Pitfalls
Normal variants that can mislead
Multiple ossification centres in the trochlea and
olecranon epiphyses. These are common normal
variants.
The lateral epicondyle is seemingly well away
from the humerus. This is a common normal
finding. Note that the epicondyle parallels the
cortex of the adjacent humeral metaphysis—a
characteristically normal feature.
Puzzled by the appearance of the
epicondyles?
▪ On the lateral projection do not be alarmed at seeing the
medial epicondyle situated very far posteriorly (p. 108).
This is its normal position.
▪ The external (ie lateral) epicondyle can be normal but
seemingly widely separate from the humerus. The rule to
apply: when normal, its lateral border is always parallel to
the cortex of the adjacent humeral metaphysis (p. 112).
Misleading lines
Normal elbow. This AP radiograph shows a
misleading RC line (p. 104).
Normal elbow. This capitellum is only partly
ossified (normal for age) and the anterior
humeral line rule (p. 101) cannot be applied.
References
1. Dormans JP, Rang M. The problem of Monteggia
fracture—dislocations in children. Orthop Clin North
Am. 1990;21:251–256.
2. David-West KS, Wilson NI, Sherlock DA, et al.
Missed Monteggia injuries. Injury. 2005;36:1206–
1209.
3. Hartenberg MA. Ossification centers of the
pediatric elbow: a rare normal variant. Pediatr
Radiol. 1986;16:254–256.
4. Goodwin SJ, Irwin G. Normal variation in the
Appearance of Elbow Ossification Centres. Brit Soc
Paed Radiol annual meeting: Southampton; 2011.
5. Fowles JV, Slimane N, Kassab MT. Elbow dislocation
with avulsion of the medial humeral epicondyle. J
Bone Joint Surg Br. 1990;72:102–104.
6. El-Khoury GY, Daniel WW, Kathol MH. Acute and
chronic avulsive injuries. Radiol Clin North Am.
1997;35:747–766.
7. Miles KA, Finlay DB. Disruption of the
radiocapitellar line in the normal elbow. Injury.
1989;20:365–367.
8. Donnelly LF, Klostermeier TT, Klosterman LA.
Traumatic elbow effusions in pediatric patients: are
occult fractures the rule? Am J Roentgenol.
1998;171:243–245.
9. Griffith JF, Roebuck DJ, Cheng JC, et al. Acute elbow
trauma in children: spectrum of injury revealed by
MR imaging not apparent on radiographs. Am J
Roentgenol. 2001;176:53–60.
10. Cheng JC, Ng BK, Ying SY, Lam PK. A 10 year study
of the changes in the pattern and treatment of 6,493
fractures. J Pediatr Orthop. 1999;19:344–350.
11. Rogers LF, Malave S, White H, et al. Plastic bowing,
torus and greenstick supracondylar fractures of the
humerus; radiographic clues to obscure fractures of
the elbow in children. Radiology. 1978;128:145–150.
12. Reynolds RA, Jackson H. Concept of treatment in
supracondylar humeral fractures. Injury.
2005;36(Suppl 1):S51–S56.
13. Handelsman JR. Management of fractures in
children. Surg Clin North Am. 1983;63:629–670.
14. Berman L. Personal communication, 2013.
15. Borne VD, Maaike PJ, Benjamin WL, et al. The distal
radioulnar joint: persisting deformity in well reduced
distal radius fractures in an active population. Injury
Extra. 2007;38:377–383.
8
Adult elbow
Normal anatomy
AP view 116
Lateral view 116
Radiocapitellar line 117
Elbow fat pads 117
Analysis: three questions to answer
Are the fat pads normal on the lateral view? 118
Is the cortex of the radial head and neck smooth on
both views? 119
Is the radiocapitellar line normal? 120
Common injuries
Fracture of the head or neck of the radius 121
Fracture of the olecranon 122
A rare but important injury
The Monteggia injury 123
Pitfalls
Normal variants 124
A child's developing skeleton is vulnerable to
specific elbow injuries unlike those that affect an
adult. Paediatric elbow injuries are dealt with
separately in Chapter 7.
The standard radiographs
▪ AP view in full extension.
▪ Lateral with 90° flexion.
▪ Routine in some departments3: the radial head–
capitellum view (p. 121).
Regularly overlooked injuries
▪ Fracture of the radial head or neck.
▪ Monteggia injury1,2.
Abbreviations
AP, anterior-posterior; RC, radiocapitellar.
Normal Anatomy
AP view
The olecranon is obscured by the humerus. The capitellum
is lateral and articulates with the radial head. The trochlea
is medial and articulates with the ulna.
Lateral view
Radiocapitellar line
On the lateral view: the line to draw is along the long axis
of the proximal 2–3 cm of the shaft of the radius. This line
should pass through the capitellum.
Elbow fat pads
Two pads of fat are situated close to the cortex of the distal
humerus. Referred to as the anterior and posterior fat
pads, these are external to the synovial lining of the joint.
The fat pads are never visualised on the AP projection.
Look for them on the lateral view. The fat is seen as a dark
streak in the surrounding grey soft tissues.
▪ The anterior fat pad will be seen in most (but not all)
normal elbows and is closely applied to the humerus.
▪ The posterior fat pad is not visible on the radiograph of a
normal elbow because it is situated deep within the
olecranon fossa. Because the elbow is radiographed in the
flexed position this fat shadow is hidden by the overlying
bone.
Analysis: three questions to answer
If the AP and lateral radiographs appear normal it is
important that the images are again checked in a
methodical manner. Ask yourself three questions.
Question 1—Are the fat pads normal
on the lateral view?
The same principles apply as for the paediatric elbow (p.
102). Recap:
▪ Displaced anterior fat pad = possible fracture.
▪ Displaced posterior fat pad = probable fracture.
▪ Fat pads not displaced = occasionally a fracture.
The black stripe against the anterior cortex of
the humerus is a normally positioned anterior fat
pad. Normal elbow.
The anterior fat pad is lifted off the bone (“the
sail sign”) indicating an effusion. This is a
variation of the standard lateral view (angled as
described on p. 121). The fracture involving the
head and neck of the radius is well shown.
Displaced anterior and posterior fat pads.
Fracture head of radius (irregularity of the
anterior cortex).
Large effusion shown by the gross displacement
of the anterior and posterior fat pads. No obvious
fracture on this radiograph. The AP will need
careful scrutiny—particularly, the appearance of
the head of the radius.
Question 2—Is the cortex of the radial
head and neck smooth on both
views?
▪ No crinkle, no step, no irregularity.
▪ Zoom up on the image and check that the cortex is
smooth, smooth, smooth.
Displaced fat pads. The head of the radius
shows a slight crinkle in the cortex: undisplaced
fracture.
Radial head and neck. Normal cortices. No
step, no crinkle, no angulation.
Fracture involving the head and neck of the
radius. An intra-articular fracture line and a step
in the lateral cortex.
Fracture involving the head and neck of the
radius. Subtle break in the articular cortex.
Fracture neck of radius. Subtle fracture line in
the lateral cortex.
Question 3—Is the radiocapitellar
(RC) line normal?4
Anterior dislocation of the head of
radius.
The golden rule: on a normal lateral radiograph a
line drawn along the long axis of the proximal 2–3
cm of the shaft of the radius should pass through
the capitellum.
Clinical impact guideline.
Problem: Fat pad displacement but no fracture
or dislocation identified after careful examination
of the AP and lateral views…
Next steps:
▪ No additional radiographs needed. Manage as
for a radial head fracture.
▪ Clinical review in 10 days…
If clinically normal, no further radiography. If
clinically abnormal, obtain repeat radiographs.
The common injuries
Fracture of the head or neck of the
radius
In the adult, these fractures represent 50% of all fractures
at the elbow.
An
additional
radiograph.
Some
Emergency
Departments routinely add a third (an angled) projection to
the standard AP and lateral views. This is termed the radial
head-capitellum view3. The patient is positioned as for the
lateral view but the tube is angled 45° to the joint. This is
an excellent projection for evaluation of the radial head.
Angled projection. Fracture of radial head and
neck.
Fracture through the radial neck.
Slight kink indicates a fracture of the radial
neck.
Fracture of the radial head and neck.
Fracture of the olecranon5
Accounts for 10-20% of adult elbow fractures.
Undisplaced fracture involving the olecranon.
Displaced fracture of the olecranon.
Comminuted fracture of the olecranon.
The major fragment is widely displaced
posteriorly.
A rare but important injury
The Monteggia injury 1,2,5
This combination injury represents less than 5% of all
elbow fractures or dislocations4–6. Often referred to as a
Monteggia fracture–dislocation or a Monteggia lesion. It
comprises a fracture of the ulna and dislocation of the head
of the radius.
Background: the forearm bones can be regarded as
acting as a single functional unit as they are bound
together by the strong interosseous membrane and
ligaments. Consequently, a displaced or angulated fracture
of just one of these two bones will be accompanied by an
injury affecting the other bone—invariably a dislocation.
Whenever there is a displaced fracture of the ulna, but an
intact radius it is important to assess the proximal radioulnar joint for a dislocation of the head of the radius
utilising the radiocapitellar line. This assessment will show
whether a Monteggia injury is present.
Clinical impact guideline: early diagnosis is clinically
very important… “the key to a good result following a
Monteggia fracture–dislocation is prompt recognition of the
injury pattern”2.
Monteggia injury. Comminuted, displaced, and
angulated fracture of the ulna. Intact radius.
Abnormal
radiocapitellar
line
reveals
a
dislocation of the head of the radius. This injury
follows the principle of the Two Bone Rule (p.
146).
An angled projection (see p. 121) showing
normal alignment of the head of the radius with
the capitellum. The radiocapitellar line (p. 117) is
unquestionably normal.
Pitfalls
A common normal variant. The tuberosity of
the radius can cause a difficulty. The tendon of
the biceps muscle is attached to this tuberosity.
On the lateral view the normal tuberosity may be
seen en face and, because of the relative density
of the margins of the tuberosity, it can appear as
an oval lucency. This lucency may be mistaken for
an area of bone destruction or a bone cyst6. The
apparent “cyst” in the shaft of this radius is
entirely normal. Another example is evident on p.
123.
An occasional normal variant. This upper
arm was lacerated by a glass bottle. The lateral
radiograph showed this density anterior to the
shaft of the humerus above the elbow. This is not
a glass fragment. It is an atavistic supracondylar
spur.
A supracondylar spur occurs in 1–2% of normal
individuals. It is a normal structure in some
mammals, particularly climbing animals7. In
clinical practice it is usually an incidental and
unimportant finding. Occasionally a spur may
cause symptoms usually related to its effect on
the median or ulnar nerve.
References
1. David-West KS, Wilson NI, Sherlock DA, et al.
Missed Monteggia injuries. Injury. 2005;36:1206–
1209.
2. Ring D, Jupiter JB, Simpson NS. Monteggia
fractures in adults. J Bone Joint Surg. 1998;80:1733–
1744.
3. Greenspan A, Norman A. The radial head,
capitellum view: useful technique in elbow trauma.
Am J Roentgenol. 1982;138:1186–1188.
4. Miles KA, Finlay DB. Disruption of the
radiocapitellar line in the normal elbow. Injury.
1989;20:365–367.
5. Rogers LF. Radiology of skeletal trauma. 3rd ed.
Churchill Livingstone; 2002.
6. Keats TE, Anderson MW. Atlas of normal Roentgen
variants that may simulate disease. 9th ed. Elsevier;
2012.
7. Kessel L, Rang M. Supracondylar spur of the
humerus. J Bone Joint Surg. 1966;48B:765–769.
9
Wrist & distal forearm
Normal anatomy
PA projection: bones and joints 126
Lateral projection: bones and joints 127
Analysis: the checklists
The PA view 128
The lateral view 130
The scaphoid series 132
The common fractures
Fractures of the distal radius 136
Fractures of the distal radius in children 140
Fractures of the distal ulna 142
Scaphoid fracture 144
Triquetral fracture 145
Subluxations and dislocations
Distal radio-ulnar joint subluxation 146
Scapho-lunate separation 147
Rare but important injuries
Fractures of the other carpal bones 148
Subluxations/dislocations of the carpus 148
Normal variants that can mislead
Normal radial beak; normal longitudinal ridges;
accessory ossicles 151
Regularly overlooked injuries
▪
▪
▪
▪
Undisplaced fracture of distal radius.
Dislocation involving the lunate.
Greenstick fracture.
Triquetral fracture.
The standard radiographs
PA, Lateral, Scaphoid series.
Abbreviations
AVN, avascular necrosis; C, capitate; L, lunate;
PA, posterior-anterior (view); R, radius.
Normal anatomy
PA projection: bones and joints
The articular surface of the radius lies distal to that of the
ulna in 90% of normal people.
The carpal bones are arranged in two rows, bound
together by strong ligaments:
▪ The joint spaces are uniform in width: 1–2 mm wide in the
adult.
▪ Adjacent bones have parallel/congruous surfaces.
▪ Abnormally narrow spaces are invariably due to
radiographic projection or to age related degenerative
change; rarely due to injury.
▪ Abnormally wide spaces are likely to indicate damaged
ligaments.
Lateral projection: bones and joints
The dorsal cortex of the distal radius is completely smooth
—no crinkles, no irregularity. This cortex should be as
smooth as a baby's bottom.
The alignment of the carpal bones may appear confusing
but identifying the important anatomy is actually very
simple. Don't worry about the overlapping bones. Just
think: apple, cup, saucer.
The distal radius, the lunate and the capitate
articulate with each other and lie in a straight
line; like an apple in a cup sitting on a saucer.
The radius (R, the saucer) holds the lunate (L, the
cup) and the cup of the lunate contains the
capitate (C, the apple).
The articular surface of the radius has a slight
but definite palmar (ie anterior) tilt. The angle of
tilt is usually about 10°, but ranges from 2° to
20°.
Analysis: the checklists
The PA view will appear fairly comforting to an
inexperienced observer because all of the carpal bones are
clearly shown. The lateral radiograph may appear
terrifyingly complex and difficult to analyse because of the
numerous overlapping bones. There is a very clear
message: do not be afraid!
The lateral view is diagnostically very, very, important, so
we will show you how to quickly and confidently analyse
every lateral radiograph using a simple checklist.
The PA view
Analysis: ask yourself five questions.
Questions 1–4 apply to all adults. Question 5 applies to all
children.
1. Is the radial articular surface and/or the ulna styloid
process whole and intact?
No = undisplaced fracture.
2. Does the radial articular surface lie distal to the ulna?
No = suspect disruption at the radio-ulnar joint.
3. Is the scaphoid bone intact and normal?
No = fracture.
4. Is the scapho-lunate distance less than 2 mm wide?
No = suspect a tear of the scapho-lunate ligaments (p.
147).
5. In children: does the radial cortex show any angulation
or any suggestion of a localised bulge?
Yes = Greenstick or Torus fracture.
Normal PA wrist.
The answer to questions 1–4 is yes.
Abnormal PA wrist.
(1) Subtle increase in density of the metaphysis of
the radius suggests an impacted fracture.
(2) Widening of the distal radio-ulnar joint and
the ulnar articular surface lies distal to the
immediately adjacent radial articular surface. The
radio-ulnar joint is disrupted.
Abnormal PA wrist.
A subtle lucent line crosses the metaphyseal–
diaphyseal region of the radius.
Note the slight bulging of the adjacent cortex.
Fracture of the radius. A Torus fracture (p. 18)
The lateral view
Analysis: ask yourself five simple questions on each and
every lateral view. No exceptions.
If you ask and correctly answer these five questions you
will detect all the subtle and clinically important
abnormalities.
1. Is the radial articular surface intact?
No = undisplaced fracture.
2. Is the dorsal cortex of the distal radius smooth?
Specifically:
□ Is the cortex as smooth as a baby's bottom?
□ No crinkle, no angulation, no bulge, no buckling?
□ Are you sure? Check the dorsal cortex one more time.
No, it is not smooth = undisplaced fracture.
3. Is the palmar tilt (normal range 2–20°) of the articular
surface of the radius normal?
No = suspect an impacted fracture.
4. Is there a bone fragment lying posterior to the carpal
bones?
Yes = Triquetral fracture.
5. Is there a bone sitting in the cup of the lunate?
No = carpal dislocation involving the lunate (pp. 148–
150).
Normal lateral wrist.
Normal palmar tilt. Dorsal cortex of the radius is
as smooth as a baby's bottom. The cup of the
lunate is full—it articulates normally with the
capitate.
The three bones (radius, lunate, capitate) are in
line. Normal appearance.
Child. Injured wrist. Slight kink and angulation
in the dorsal cortex of the radial diaphysis.
Greenstick fracture.
The scaphoid series
Many undisplaced scaphoid fractures are not visualised on
the two standard (wrist) views. Two extra views produces a
better return. Therefore, a four view scaphoid series is
essential and should be requested whenever there is
‘snuffbox’ tenderness:
The two additional images will vary between Emergency
Departments. Importantly, two of the four projections will
always include a true PA and a true lateral of the wrist.
Scaphoid fractures are mainly hairline fractures and
lucent; they are not sclerotic. Occasionally the fracture is
displaced.
Analysis: ask yourself three questions.
1. Does the scaphoid appear intact on each of the four
views?
No = fracture (see p. 144).
2. Is the distal radius—particularly the styloid process—
intact?
No = fracture (see pp. 136–141).
AND
3. Have I checked the PA and lateral views step-by-step
(see pp. 128–130)?
No = start checking.
Snuffbox tenderness. A four view scaphoid
series.
A four view scaphoid series. Normal.
Hairline fracture (arrow) through the waist of
the scaphoid.
This is the most typical appearance.
Fracture of the distal pole of the scaphoid.
Distal pole fractures are comparatively
infrequent.
Fracture of the proximal pole of the scaphoid.
Proximal pole fractures are comparatively
infrequent.
One view from a scaphoid series. The scaphoid
is intact but there is an undisplaced fracture of
the radial styloid (arrow). The distal radius must
be evaluated very carefully on every scaphoid
series—snuffbox tenderness is often due to a
fracture of the radius.
Wrist myths
Inevitably there will be some soft tissue swelling over the
site of an injury due to simple bruising, a ligamentous
injury, a fracture, or a combination of all of these. This soft
tissue swelling on the radiograph is not particularly helpful
in terms of radiological diagnosis. There have been claims
that the appearance of some soft tissue fat stripes around
the wrist can be helpful, but this is not the case1.
The common fractures
Patient age and the common fractures
Fractures of the distal radius
These injuries result from a fall on the outstretched hand.
Obvious fractures
▪ Colles' fracture—radial fracture with dorsal displacement.
▪ Smiths' fracture—radial fracture with ventral
displacement.
Subtle fractures/careful diagnosis
▪ A crinkle, or any irregularity of the cortex of the dorsal
aspect of the distal radius.
▪ An impacted and undisplaced fracture:
□ The only abnormality may be a very slight increase in
the density of the radial metaphysis and/or
□ Loss of the normal palmar tilt of the radial articular
surface (see p. 127).
▪ A longitudinal fracture:
□ Frequently undisplaced (see p. 139)
□ Barton-type fractures (see p. 138).
Irregular and crinkled surface of the dorsal
cortex of the radius.
Undisplaced fracture.
Slight angulation of the dorsal cortex of the
radius. Greenstick fracture.
Slight bulge/angulation (arrow) on the dorsal
cortex of the radius. A Torus (or Greenstick)
fracture.
Normal. The palmar tilt of the articular surface
of the radius varies between 2° and 20°. If this
tilt is absent, or reversed, then an impacted
fracture is probable/almost certain.
The radius shows: (1) irregularity of the dorsal
cortex; (2) increase in density of the metaphysis;
(3) reversal of the normal palmar tilt of the
articular surface. Conclusion: impacted fracture.
Barton fracture. A shearing fracture involving
the dorsal cortex of the distal radius and its
articular surface; ie it extends into the wrist joint.
When the radial fragment is displaced it moves
posteriorly and carries the carpus with it.
Often
incorrectly
assumed
to
be
any
longitudinal fracture of the distal radius.
Clinical
impact
guideline:
Barton-type
fractures are important to recognise as these are
very unstable injuries. Careful evaluation of the
radiographs is essential in order to make the
correct diagnosis.
Reverse Barton fracture (volar Barton
fracture). This Barton fracture variant is present
when the intra-articular fracture involves the
anterior cortex of the radius.
In all instances the frontal and lateral
radiographs need to be evaluated as a pair.
Sometimes an abnormality will be detected on the
frontal view and not on the lateral radiograph,
and vice versa. This patient had fallen onto an
outstretched hand.
The PA view: a longitudinal fracture involving
the articular surface of the radius, a fracture of
the ulnar styloid process, and slight disruption of
the radio-ulnar joint.
The lateral view: slight irregularity of the
dorsal cortex of the distal radius. Otherwise the
appearances are normal.
Principal
diagnosis:
undisplaced
intraarticular fracture of the distal radius.
A secondary feature: subluxation at the distal
radio-ulnar joint. Instability at this joint is an
occasional longer term complication.
Fractures of the distal radius in
children
Sometimes these fractures are obvious. Many are very
subtle.
Greenstick fracture (left).
Slight angulation of the radial cortex. Note how
the intact periosteum acts like a hinge.
Torus fracture (right).
Slight bulge of the radial cortex.
Greenstick fracture.
Torus fracture.
A Greenstick fracture often results from a fall
with the forearm positioned at an angle to the
ground (a). A Torus fracture tends to result from
the forearm being in a more vertical position (b).
Salter–Harris fractures.
These fractures involve the growth plate. They
are described in detail on pages 15–17.
This lateral radiograph shows a fracture
through the growth plate of the radius. The
epiphysis is displaced posteriorly. The fracture
also extends into the metaphysis of the radius.
This is a Salter–Harris Type 2 fracture.
Fractures of the distal ulna
Ulna styloid fracture.
The two patients shown above had each sustained
a Colles' fracture. The lateral radiographs are not
shown here.
An undisplaced fracture of the ulna styloid
often accompanies a Colles' fracture, as shown
above. In general, this particular ulna fracture is
not itself clinically important.
However, if an ulna styloid fracture is displaced
(as in the right hand image), then this can
indicate that serious disruption of the distal
radio-ulnar joint has occurred2. Consequently,
instability at this joint is a possible longer term
complication.
Nightstick fracture.
A Nightstick fracture is an isolated fracture of the
ulna caused by a direct blow to the ulnar border
of the forearm during a fight, fall, sporting
activity, or car accident. Commonly, but not
always, the fracture involves the middle third of
the shaft of the ulna.
The term Nightstick fracture was coined
because of the usual forearm defence against
receiving a head injury when warding off a
policeman's nightstick, or a truncheon, a crowbar,
or a baseball bat. The arm is brought up above
the head and consequently it is the ulna that
receives the downward blow.
Clinical impact guideline: most Nightstick
fractures are undisplaced or minimally displaced.
However, if there is more than 50% displacement
the fracture will invariably require open
reduction and internal fixation.
Direct blow to the shaft of the ulna during a
brawl. A minimally displaced fracture at the site
of the blow. A Nightstick fracture.
Scaphoid fracture
This injury mainly affects young adults (see p. 136). Carpal
bone injuries—including scaphoid fractures—are very rare
in children.
A recent scaphoid fracture is never sclerotic (ie
white/dense).
Most scaphoid fractures will be evident on the initial
scaphoid series3. Contrary to conventional teaching, the
number of occult fractures revealed by repeat radiography
at 10 days is very low4,5. Persisting clinical suspicion
warrants an MRI, not more plain film radiography.
Clinical impact guideline: If a scaphoid fracture is
initially overlooked and the patient is managed incorrectly
then any of the following may occur: non-union, delayed
union, avascular necrosis (AVN) of the proximal fragment,
or osteoarthritis.
Scaphoid fracture. Fractures may involve the
waist, proximal pole, or distal pole. The majority
are hairline and undisplaced. A fracture across
the waist jeopardises the blood supply of the
proximal fragment, because the majority of the
arterial supply enters via the distal pole/waist
before feeding the proximal pole6.
Risk of AVN following a scaphoid fracture
Site of fracture Risk of AVN
Waist
High
Proximal pole
Very high
Distal pole
Nil
Triquetral fracture
A small fragment or flake of bone lying posterior to the
proximal row of the carpus on the lateral view invariably
represents an avulsion fracture of the triquetrum (the
triquetral bone). This fracture accounts for approximately
20% of all carpal bone fractures5.
Occasionally a triquetral fracture may occur when there
is a perilunate dislocation of the carpus6. This emphasizes
the importance of two of our basic principles:
1. Avoid a premature “satisfaction of search” approach.
Complete the checklist.
2. Always check the saucer, cup, apple alignment on every
lateral radiograph. Remember: the cup of the lunate
should never be empty (see pp. 148–150).
Clinical impact guideline: if a solitary triquetral
fracture is detected, the patient can be reassured that the
injury will be treated conservatively, mainly by providing
pain relief, and an excellent outcome is anticipated.
Triquetral fracture.
The small fragment of bone is an avulsed
fragment from the triquetrum. The posterior
position of the fragment on the lateral radiograph
is typical.
Subluxations and dislocations
Distal radio-ulnar joint subluxation
Disruption of this joint is a relatively frequent finding with
a Colles' fracture, occurring in 18% of cases7. Isolated
traumatic dislocation or subluxation of this joint is rare.
Colles' fracture. In this patient the radio-ulnar
joint is also disrupted.
Radial shaft fracture. Whenever there is a
fracture of the radial shaft with angulation or
over-riding and an intact ulna, there will also be
separation of the distal radio-ulnar joint. This
combination injury is termed a Galeazzi injury.
This fracture–dislocation follows the principle of
the Two Bone Rule (see below).
The Two Bone Rule
In a two-bone system8 such as the radius and
ulna, where the bones are tightly bound together
by an interosseous membrane and/or ligaments,
the two bones can be regarded as acting as a
single functional unit. In effect, they form a
bound-together ring. Consequently, if only one of
the bones is fractured and displaced or angulated
resulting in shortening there must be a
disturbance somewhere else. That disturbance
may be at a joint (proximally or distally) and
these joints must be carefully evaluated. Apply
these guidelines when a forearm fracture is
present:
▪ Displaced ulna fracture + normal shaft of
radius …dislocation of the head of the radius (a
Monteggia injury).
▪ Displaced radial fracture + normal shaft of ulna
…distal radio-ulnar joint separation (a Galeazzi
injury).
Scapho-lunate separation
The scapho-lunate joint is particularly susceptible to
ligamentous injury. In adults, following an injury to the
wrist, any widening of the normal space (normal = 2
mm)between the lunate and the scaphoid bones on the PA
radiograph is strongly suggestive of a ligamentous tear.
This injury is particularly common in the elderly when the
ligaments may be friable.
Clinical impact guidelines: The syndrome of chronic
wrist pain located around the scapho-lunate joint due to
scapho-lunate instability is a very troublesome problem9. In
the elderly, this injury will usually be treated
conservatively. In younger patients, surgery will be
considered in order to restore full function and a pain free
wrist.
Actors and actresses rule the roost.
Terry Thomas was a 20th-century English comic
actor, always grinning and showing a trademark
gap between his upper incisors. Madonna, the
21st-century actress and singer, used to possess a
similar dental configuration. An abnormal gap
between the scaphoid and the lunate bones
indicating a tear of the scapho-lunate ligaments
(as shown here) is often termed the Terry Thomas
or Madonna sign.
Rare but important injuries
Fractures of the other carpal bones
▪ 95% of carpal bone fractures involve the scaphoid or the
triquetral bones. Fractures of the other bones do occur
but are relatively uncommon.
▪ A fracture of the hamate may occur when a fist puncher
has injured the base of his 4th or 5th metacarpal (pp. 167–
168).
▪ The hook of the hamate may also fracture as a result of a
direct blow to the carpus or as an avulsion injury
associated with racquet sports or a golf swing5,6.
Hamate fracture (arrow).
The patient had punched a wall.
Subluxation/dislocations of the
carpus
These injuries are infrequent but are usually centred
around the lunate bone. The following rule is the key to
their detection, and must be applied to all lateral views:
The cup of the lunate should never be empty.
Lunate dislocation and perilunate dislocations
of the carpus6,10,11
These dislocations are not difficult to recognise provided
that the basic anatomy on the lateral view is properly
understood (see p. 127). The distal radius, the lunate and
the capitate articulate with each other and lie in a straight
line. Consequently, the question to ask on all lateral views
is:
‘Does a bone (the capitate) sit in the cup of the lunate?’
Lunate dislocation, lateral view.
The lunate dislocates anteriorly. On the lateral
view the cup of the lunate is empty. The radius
and the capitate remain in a straight line.
Lunate dislocation, PA view.
Emphasis is often unnecessarily placed on the
appearance of the lunate on the PA view because
a dislocated lunate can adopt a triangular
configuration instead of its normal ‘squareish’
contour.
In practice, this sign is more interesting than
helpful12 because it is much easier and more
definitive to diagnose a dislocation by assessing
the lateral view.
Perilunate dislocation11. The whole of the
carpus (except for the lunate) is displaced
posteriorly. Inspection of the lateral view reveals
the misalignment of the carpal bones. A
perilunate dislocation is often accompanied by a
scaphoid fracture. Occasionally it is also
associated with a triquetral fracture6.
Satisfaction of search. Detection of a
scaphoid fracture (if present) on the PA view may
comfort the unwary who then fail to analyse the
lateral view carefully. The unwary will overlook
the following…
▪ The cup of the lunate is empty.
▪ The radius and the lunate remain in a straight
line but the capitate lies posteriorly and out of
line.
▪ In other words: the apple, the cup and the
saucer do not line up. A perilunate dislocation.
Carpal subluxations6,8
Ligamentous tears or ruptures can affect any of the small
joints of the carpus. Such injuries may result in carpal
instability, pain, and reduced function.
Normally, the joint spaces between the intercarpal joints
measure no more than 2 mm in the adult. Widening of any
of these spaces raises the possibility of an intercarpal
subluxation. In addition, subluxation will be suggested
because adjacent bones do not have parallel or congruent
surfaces.
Help is always available. If you are in any doubt as to
whether there is true widening at a carpal joint, you can
always obtain a radiograph of the uninjured wrist. This will
allow comparison between the injured and uninjured sides.
Clinical impact guideline: Referral to a hand surgeon
for a specialist clinical evaluation will be necessary when
joint widening or lack of parallelism of adjacent surfaces is
noted.
Normal variants that can mislead
Normal radial beak. It is quite common for
there to be a normal projection of bone—a beak—
protruding from the lateral aspect (arrows) in the
region/site of the fused growth plate.
Normal longitudinal ridges. In most mature
skeletons the dorsal cortex of the distal radius is
a single smooth line. However, it is a common
normal variant for the dorsal cortex to contain/be
seen as two or three smooth longitudinal ridges
(arrows).
Accessory ossicles.
Several accessory carpal bones do occur; all are
rare. One accessory ossicle, the os centrale carpi,
can be confused with an avulsed fragment from
the scaphoid bone. Its location (above) projected
adjacent to the medial aspect of the distal pole of
the scaphoid is typical.
References
1. Annamalai G, Raby N. Scaphoid and pronator fat
stripes are unreliable soft tissue signs in the
detection of radiographically occult fractures. Clin
Radiol. 2003;58:798–800.
2. McRae R, Esser M. Practical Fracture Treatment.
5th ed. Churchill Livingstone; 2008.
3. Brondum V, Larsen CF, Skov O. Fracture of the
carpal scaphoid: frequency and distribution in a well
defined population. Eur J Radiol. 1992;15:118–122.
4. Low G, Raby N. Can follow-up radiography for acute
scaphoid fracture still be considered a valid
investigation? Clin Radiology. 2005;60:1106–1110.
5. Raby N. Imaging of wrist trauma. Davies AM,
Grainger AJ, James SJ. Imaging of the Hand and
Wrist. Springer Verlag; 2013.
6. Goldfarb CA, Yin Y, Gilula LA, et al. Wrist fractures:
what the clinician wants to know. Radiology.
2001;219:11–28.
7. Malik AK, Pettit P, Compson J. Distal radioulnar joint
dislocation in association with elbow injuries. Injury.
2005;36:324–329.
8. Maaike PJ, van't Hof BW, Prins HJ, et al. The distal
radioulnar joint: persisting deformity in well reduced
distal radius fractures in an active population. Injury
Extra. 2007;38:377–383.
9. Mayfield JK. Mechanism of carpal injuries. Clin
Orthop Relat Res. 1980;149:45–54.
10. Panting AL, Lamb DW, Noble J, et al. Dislocations of
the lunate with and without fracture of the scaphoid.
J Bone Joint Surg Br. 1984;66B:391–395.
11. Herzberg TJ, Comtet JJ, Linscheid RL, et al.
Perilunate dislocations and fracture-dislocations: a
multicenter study. J Hand Surg Am. 1993;18A:768–
779.
12. The Wrist. Chan O. ABC of Emergency Radiology.
3rd ed. Wiley Blackwell; 2013.
10
Hand & fingers
Normal anatomy
PA and oblique views 154
The thumb 155
The carpometacarpal joints 156
Analysis: the checklist
Adopt a three-step approach 158
The common injuries
Fractures of the phalanges or metacarpals 160
Uncommon but important injuries
Fractures and dislocations involving the thumb 164
Carpometacarpal joint dislocations 167
The 4th and 5th carpometacarpal joints on the PA
radiograph 168
Pitfalls
Mobile basal joint of the thumb 169
Additional bones 169
Accessory epiphyses 170
The standard radiographs
Depends on site of injury:
▪ Injury to a metacarpal or several phalanges: PA
of hand and oblique of entire hand and
wrist.
▪ Injury to the thumb or to a single digit: PA and
lateral of the digit.
Regularly overlooked injuries
▪ Dislocations at 4th & 5th CMC joints.
▪ Fractures at base of 4th or 5th MCs.
▪ Fracture of the hamate.
Abbreviations
CMC, carpometacarpal;
IPJ, interphalangeal joint;
MC, metacarpal;
MCPJ, metacarpophalangeal joint;
PA, posterior-anterior (view).
Normal anatomy
Knowledge of the anatomical attachments of (a few)
tendons and ligaments is essential. A seemingly trivial
fragment of bone on the radiograph may indicate that a
particular tendon or ligament is no longer anchored to the
bone. Failure to recognise the functional implication can
lead to inappropriate management.
PA view of hand and wrist.
The collateral ligaments arise from the lateral
and medial margins of each metacarpal and each
phalanx. They extend across the joint and insert
into the same margin at the base of the adjacent
phalanx.
Oblique view of hand and wrist.
The extensor tendons insert into the dorsal
surface at the base of each phalanx.
The volar plate is a fibrous thickening of the
joint capsule on the palmar aspect of each joint. It
is attached to the bases of the adjacent
phalanges.
The thumb
Thumb. The tendon of the abductor pollicis
longus is inserted into the radial aspect of the
intra-articular portion of the base of the first
metacarpal. This is the important anatomical
feature in a Bennett's fracture dislocation.
Thumb.
The stability of the carpometacarpal (CMC) joint
of the thumb depends on fairly lax but very tough
capsular ligaments1. The deep ulnar ligament is
the thickened part of the capsule on the palmar
aspect of the 1st CMC joint. This strong ligament
extends from the first metacarpal to the
trapezium. The capsular ligaments and the shape
of the first CMC joint (ie the trapezium–
metacarpal joint) enables the thumb to adopt an
extraordinary degree of mobility including the
crucial ability of opposition.
1st CMC joint = basal joint of the thumb.
The carpometacarpal (CMC) joints
The 2nd and 3rd metacarpals are attached to
the distal row of the carpal bones by thick,
strong, ligaments.
The 4th and 5th metacarpals have fewer
ligaments anchoring them2. These two CMC joints
are consequently: (a) very mobile, and (b)
vulnerable to injury.
On the PA view of the hand:
▪ The articular cortex at the base of each
metacarpal parallels the articular surface of the
adjacent carpal bone.
▪ The CMC joint spaces are clearly seen; they are
equal (approximately1–2 mm) in width.
▪ The 2nd to 5th CMC joints are visualised as a
zigzag tram line3 (see opposite).
The normal CMC joints
On the PA radiograph, the joint surfaces of the
2nd through to the 5th metacarpal and their
adjacent carpal bones articulate, and their
articular surfaces parallel one another. These
joints are thus seen as a zigzag tram line3, shown
as a thick dark line on this drawing.
The zigzag line is analogous to “seeing the light
of day” through each of the CMC joints.
Useful rule:
On a normal PA view of the hand there will
always—yes, always—be “the light of day” seen
between the bases of the 4th and 5th metacarpals
and the hamate bone.
A stylised drawing of the important alignment
between the bases of the hamate and the 4th and
5th CMC joints. Understanding the radiographic
appearance of these two joints on the PA view is
important. In some people the normal joints look
like (a); in others the normal joints look more like
(b).
See also pp. 167–168.
Analysis: the checklist
Adopt a three-step approach:
1. Target the precise clinical site of injury.
2. Search for fractures and for any evidence of
subluxation/dislocation.
3. Review the relevant muscle and ligamentous
attachments because a small fracture may indicate a big
loss of function.
Hand, PA view.
Check
for
fractures,
dislocations,
and
subluxations; check whether the 4th and 5th
carpometacarpal (CMC) joints show “the light of
day” (p. 157); check the basal joint of the thumb;
if there is a fracture of the 1st metacarpal
determine whether it is intra-articular (Bennett's
fracture) or extra-articular. This is a normal PA
view.
Hand, oblique view.
Check
for
fractures,
dislocations
and
subluxations. This, the routine second view, will
invariably clarify/categorise any abnormality that
is suspected on the PA radiograph. This is a
normal oblique view.
Injury to the basal joint of the thumb.
An intra-articular fracture of the base of the 1st
metacarpal.
Single digit injury.
Check for fracture and
These two patients have
injury (ie a fragment
capsular region of the
interphalangeal joint).
dislocation/subluxation.
sustained a volar plate
is detached from the
palmar aspect of an
The common injuries
Fractures of the phalanges or
metacarpals
Most fractures involving the mid-shaft of a phalanx or
metacarpal are stable and pose few clinical problems.
Phalangeal fractures are frequently managed by strapping
to an adjacent digit (ie garter strapping or buddy
strapping).
There are some “problem fractures”, for which careful
orthopaedic assessment is essential. The most common of
these are shown on the next four pages.
Avulsion of a small fragment at the base
of a phalanx.
The ligament or tendon most likely to be
compromised is indicated by the position of the
fragment:
▪ A lateral or medial fragment indicates avulsion
of the collateral ligament (left)
▪ A dorsal fragment indicates avulsion of the
extensor tendon (middle)
▪ A palmar fragment indicates an avulsion of the
volar plate.
Mallet finger.
A flexion deformity (known as a mallet or baseball
finger) of the distal phalanx.
An isolated flexion deformity is almost
impossible without either a rupture of the
extensor tendon or an avulsion fracture.
A deformity necessitates very careful clinical
examination because a fracture is present in only
25% of mallet fingers.
Volar plate fracture.
Caused by forced extension of a finger.
The detached fragment will be visualised on the
oblique view—not on the PA view.
These fractures are nearly always displaced
and thus unstable.
Spiral fracture of the shaft of a phalanx
or metacarpal.
These fractures are often unstable and significant
shortening may occur. The fracture frequently
requires open reduction and internal fixation4.
Fracture involving a joint surface.
If there is displacement and/or comminution then
surgical repair can be challenging because the
fragments are invariably very small5.
Fracture of a metacarpal neck: Boxer's
fracture.
“Boxer's fracture” is the accepted generic term
when referring to a fracture of the neck of a
metacarpal—frequently
the
4th
or
5th
metacarpal. Invariably, the fracture is consequent
on punching a solid object whilst the fist is
clenched. The solid object might be a wall or a
goal post (frustration/temper) or a chin
(brawling/fist fight).
Nomenclature. The term Boxer's fracture is
arguably a misnomer because trained boxers
rarely fracture these particular metacarpals.
Indeed, it is the untrained street fighter and not a
boxer who usually presents with this injury.
Background:
▪ A trained boxer's fracture: in the boxing ring,
the athlete strikes with the wrist in the neutral
position. The result is an occasional fracture of
the 2nd or 3rd metacarpal, but rarely a fracture
of the 4th or 5th metacarpal.
▪ A street fighter's (or scrapper's) fracture: when
the blow is struck, the wrist is flexed. The result
is a fracture of the 4th or 5th metacarpal.
Boxer's fracture. These two patients have sustained a
fracture through the neck of a metacarpal (left, 4th
metacarpal; right, 5th metacarpal).
Uncommon but important injuries
Fractures and dislocations
involving the thumb
The basal joint (ie the carpometacarpal or CMC joint) of the
thumb is remarkable. It is multifunctional. It can adduct,
abduct, oppose and circumduct (see p. 155). If the
multifunctional ability of this joint is to be maintained then
any injury close to this joint needs to be recognised,
characterized, and treated early1,6.
Distinguishing between an intra-articular and an extraarticular fracture at the base of the thumb is crucial. The
distinction determines the appropriate treatment.
Base of thumb: extra-articular fracture
The fracture line is distal to the joint capsule. Consequently
it is distal to both the deep ulnar ligament and to the
insertion of the tendon of abductor pollicis longus and
there is no involvement of the CMC joint and no risk of
dislocation.
This is important because almost all extra-articular
fractures at the base of the thumb are treated simply by
closed reduction.
Base of thumb fracture.
The fracture line is distal to the insertion of the
tendon of the abductor pollicis longus muscle.
The CMC joint is not involved.
No risk of dislocation.
Extra articular fracture, base of 1st
metacarpal.
The articular surface is not involved. The
proximal fragment remains in a stable position.
Bennett's fracture.
A fracture involving the base of the 1st
metacarpal. Crucially, the joint surface is
involved.
The larger metacarpal fragment is pulled
dorsally and radially by the abductor pollicis
longus muscle.
This injury is more properly termed a Bennett's
fracture–dislocation. It is unstable.
Early orthopaedic treatment (often open
reduction) is essential because retention of the
multiple movements at this special CMC joint are
so important4,6.
Rolando's fracture.
A comminuted intra-articular fracture of the base
of the 1st metacarpal. The comminuted fragments
often adopt a Y, V or T configuration. It is highly
unstable.
This fracture can be difficult to treat because of
the comminution and displacement of the
articular fragments.
Gamekeeper's/Skier's thumb7
▪ Rupture or severe stretching of the ulnar collateral
ligament (p. 155) at the first metacarpophalangeal joint
(MCPJ). Occasionally a bone fragment may be avulsed. A
complete tear of the ligament requires surgical repair7,8.
□ Usually the ligament alone is torn and the
radiographs appear normal.
□ If there is clinical uncertainty as to whether the
ligament is torn then stress radiographs can assist in
confirming or excluding the diagnosis. Diagnostic
ultrasound examination by a skilled practitioner is a
reliable alternative to stress radiography7,8.
Skier's thumb.
In most cases the medial collateral ligament is
torn and the standard radiographs appear
normal.
Occasionally there is an avulsion fracture of the
base of the proximal phalanx at the insertion of
the ligament.
Skier's thumb.
Fragments have been detached from the base of
the proximal phalanx of the thumb. This
represents an avulsion (rather than a tear or
stretching) of the medial collateral ligament.
Result: an unstable joint.
Killing rabbits versus a Skiing wipeout
Gamekeeper's thumb results from the chronic
stretching of the ulnar collateral ligament. So
called because of the method employed by 18th
and 19th century English gamekeepers to
dispatch and break the necks of numerous
rabbits.
Skier's thumb can occur on the ski slope when
the thumb is caught against the handle of a ski
pole during a fall or a wipeout. This causes an
acute tear of the ulnar collateral ligament. A
Skier's thumb comprises 15–20% of downhill
skiing injuries9. In some countries without snow,
the most common cause for a skier's thumb injury
is a simple fall or a non-skiing sports injury.
Carpometacarpal (CMC) joint
dislocations3,10–14
High velocity motor vehicle trauma can cause a dislocation
at any of the CMC joints.In less violent impacts (eg
punching a wall) it is the 4th and 5th metacarpals that are
most commonly dislocated.
4th or 5th CMC dislocation
Emergency Departments that receive hand injuries due to
fist fights will regularly see dislocations involving these
CMC joints. The injury commonly results from a
transmitted force along the metacarpal shaft when the
closed fist hits a solid object. It is often associated with a
fracture at the base of the affected metacarpal and/or the
adjacent metacarpal and/or the hamate. A fracture of the
dorsal surface of the hamate (seen on the oblique view)
should always raise the suspicion of a dislocation at the 5th
CMC joint.
What to look for on the PA radiograph:
▪ Effacement of the adjacent CMC joint space.
▪ Apply this analogy: can I see “the light of day” (pp. 156–
157) between the bases of the 4th and 5th metacarpals
and the hamate? In other words, any lack of parallelism
between the base of a metacarpal and the articular
surface of the adjacent carpal bone (p. 168) is very
suggestive of a dislocation.
▪ Has the head of the 5th metacarpal dropped well below
the 4th metacarpal head?
How to confirm/refute your suspicion:
▪ Check the oblique radiograph. Then, if there is still
continuing doubt, obtain a lateral view. The base of the 5th
metacarpal dislocates posteriorly.
The PA image on the left is normal and the
“light of day” is evident at the bases of the 4th
and 5th metacarpals. The PA image on the right
shows (a) fracture of the base of the 5th
metacarpal and (b) loss of the joint space at the
5th CMC joint (ie indicating a dislocation). Note
that the joint space (“the light of day”) is well
seen at the base of the 4th metacarpal indicating
that this joint is normal.
The 4th and 5th CMC joints on the PA
radiograph
Four different patients, each with a normal PA
radiograph. The corresponding artworks show
that the normal carpometacarpal (CMC) joints
can vary slightly in appearance between patients.
The difference is invariably due to the different
slope of the articular surfaces between normal
patients, as illustrated in (a) and (b) below.
However, when you inspect the PA view a joint
space (ie a black line) at the base of the 4th and
5th metacarpals will always be visible on a
normal PA radiograph, without exception.
Visualising this normal zigzag black line may be
conceptually difficult for an inexperienced
observer. The schematic drawings below explain
how a joint (“the light of day”) disappears on the
PA view when a 4th or 5th CMC joint is
dislocated.
Diagrammatic representation of the 4th and 5th
CMC joints. (a) = normal; (b) = normal; (c) =
dislocated 5th CMC joint; (d) = Dislocations at
4th and 5th CMC joints.
Pitfalls
Mobile basal joint of the thumb. The
exceptional mobility of the basal joint (ie the
trapezium–1st metacarpal joint) of the thumb
means that it may be entirely normal (above) but
appears to be subluxed. Be careful not to make
this mistake. Clinical correlation should discount
this possibility.
Additional bones. Sesamoid bones adjacent to
the first metacarpophalangeal joint (MCPJ)
should not be confused with fracture fragments.
Most hands usually have five sesamoid bones: two
adjacent to the MCPJ of the thumb, one adjacent
to the MCPJ of the index finger and one adjacent
to the MCPJ of the little finger.
Accessory epiphyses
Sometimes accessory metacarpal epiphyses—or
partial epiphyses—are present in young children.
The most common of these pseudoepiphyses
occur in the head of the 1st (thumb) metacarpal
(left and right) and at the base of the 2nd
metacarpal (centre and right). Unless the
possibility
of
an
accessory
epiphysis
is
considered, particularly at the base of the 2nd
metacarpal, then a normal developmental variant
may be read as an undisplaced metacarpal
fracture.
References
1. Kauer JM. Functional anatomy of the
carpometacarpal joint of the thumb. Clin Orthop
Relat Res. 1987;220:7–13.
2. Mueller JJ. Carpometacarpal dislocations: report of
five cases and review of the literature. J Hand Surg
Am. 1986;11:184–188.
3. Fisher MR, Rogers LF, Hendrix RW. Systematic
approach to identifying fourth and fifth
carpometacarpal joint dislocations. Am J Roentgenol.
1983;140:319–324.
4. Buchholz RW, Hickman JD, Court-Brown C.
Rockwood and Green's Fractures in Adults. 6th ed.
Lippincott Williams & Wilkins; 2006:1211–1255.
5. Khan W, Fahmy N. The S-Quattro in the
management of sports injuries of the fingers. Injury.
2006;37:860–868.
6. Howard FM. Fractures of the basal joint of the
thumb. Clin Orthop Relat Res. 1987;220:46–51.
7. Chuter GS, Muwanga CL, Irwin LR. Ulnar collateral
ligament injuries of the thumb: 10 years of surgical
experience. Injury. 2009;40:652–656.
8. Ebrahim FS, De Maeseneer M, Jager T, et al. US
diagnosis of UCL tears of the thumb and Stener
lesions: technique, pattern-based approach, and
differential diagnosis. Radiographics.
2006;26(4):1007–1020.
9. Engkvist O, Balkfors B, Lindsjo U. Thumb injuries in
downhill skiing. Int J Sports Med. 1982;3:50–55.
10. Gilula LA. Carpal injuries: analytic approach and
case exercises. Am J Roentgenol. 1979;133:503–517.
11. Pope TL, Harris JH. Harris & Harris’ The Radiology
of Emergency Medicine. 5th ed. Lippincott Williams
& Wilkins; 2012.
12. Rogers LF. Radiology of Skeletal Trauma. 3rd ed.
Churchill Livingstone; 2002.
13. Raby N. Imaging of wrist trauma. Davies AM,
Grainger AJ, James SJ. Imaging of the Hand and
Wrist. Springer Verlag; 2013.
14. Henderson JJ, Arafa MA. Carpometacarpal
dislocation. An easily missed diagnosis. J Bone Joint
Surg Br. 1987;69:212–214.
11
Cervical spine
Normal anatomy
Lateral view 172
AP Peg view 173
Long AP view 173
Analysis: the checklists
Priority 1: Lateral view checklist 174
Priority 2: AP Peg view checklist 180
Priority 3: Long AP view checklist 184
The common injuries
Injuries at C1 186
Injuries at C2 involving the Peg 188
Injuries involving the body or the posterior elements
of C2 190
C2 subluxation due to rupture of the transverse
lligament 191
Fractures C3–C7 192
Subluxations/dislocations C3–C7 193
Explaining unilateral facet joint dislocation 194
Pitfalls
On the AP Peg view; On the long AP view;
Developmental variants 195
Anterior opacity; Spasm related—delayed instability
196
Age related changes 197
Regularly overlooked injuries
The most common causes of a missed C-spine
abnormality are failure to adequately visualise
the injured region and inadequate understanding
of the C1/C2 anatomy. Therefore errors commonly
relate to:
▪ C1/C2 fractures or subluxations.
▪ Low C-spine fractures1–4, frequently involving
the C7 vertebra.
The standard radiographs
Three-view trauma series.
Abbreviations
AP, anterior-posterior projection;
C-spine, cervical spine;
C1, Atlas vertebra;
C2, Axis vertebra;
CT, computed tomography;
ED, Emergency Room/Department;
Peg, odontoid peg;
T1, first thoracic vertebra.
Normal anatomy
Lateral view
The Coffee Bean Shadow.
The anterior arch of C1 is a shadow that is always
visible on a lateral radiograph. It looks like a
reversed capital D. We call this shadow the
“Coffee Bean” shadow because we think it
resembles a coffee bean. Use it as your
anatomical starting point when assessing the C1–
C2 anatomy.
AP Peg view
Long AP view
Analysis: the checklists
Injuries are most often missed because of poor
radiographic
technique
and/or
inaccurate
film
1,2,4–6
5
interpretation
. Most errors are avoidable . Missed Cspine abnormalities occur most commonly at the top or at
the bottom of the C-spine1,2.
□ Whatever the level of violence, C-spine injuries
frequently occur at the C1–C2 level1,3,4,6.
□ The most common fracture in elderly patients following a
fall is a high cervical injury1,3.
□ Between 9% and 26% of patients with one fracture or
dislocation of the spine will have further fractures
demonstrable radiographically at other levels5.
□ If you have detected one injury you must still complete
the checklists, in order to find any additional
abnormalities.
Priority 1: Lateral view checklist
Identify the odontoid peg and assess its position and
anatomical relationship to the C1 vertebra. Overlapping
structures (eg mastoid, ear lobes, C1 vertebra) can make
this difficult. Questions 1–5 will help you to overcome this.
Ask yourself ten important questions:
1. Is the radiograph technically adequate? Ensure that the
C1–C2 articulation and the superior surface of the T1
vertebra are clearly seen.
2. Have I identified the anterior arch of the C1 vertebra
(the “coffee bean”)?
3. Is the anterior cortex of the odontoid peg (the Peg)
closely apposed to the “coffee bean”?
4. Is the line of the anterior cortex of the Peg continuous
with the anterior cortex of the body of C2? Any
displacement implies a Peg fracture or fracture of C2
body.
5. Is the line of the posterior cortex of the Peg continuous
with the posterior cortex of the body of C2? Any
displacement or break indicates a Peg fracture.
6. Is Harris' ring7 normal? A break in either the anterior or
posterior margin of the ring indicates the high
probability of a fracture of the Peg/body of C2 (p. 176).
7. Are the posterior arches of C1 and C2 intact?
8. Are the other vertebrae (C3–C7) intact (p. 192)?
9. Are the three main contour lines/arcs normal (p. 178)?
10. Are the pre-vertebral soft tissues normal (p. 179)?
Questions 2 and 3.
Recognising the anterior arch of C1 is key to
detecting the abnormalities that may involve the
C2 vertebra.
The arch looks like a small coffee bean, and is
always easy to identify on the lateral view.
The gap between the Peg and the coffee bean
should not exceed 3 mm in adults or 5 mm in
children1.
This is a normal lateral view.
Questions 4 and 5.
Check that the anterior cortex of the Peg is
continuous with the anterior cortex of the body of
C2.
Also check that the posterior cortex of the Peg
is continuous with the posterior cortex of the
body of C2. Any displacement or break in either
of these lines indicates a Peg fracture.
Question 6. Harris' Ring7. Many lateral views
will show a white ring projected over the base of
the Peg and over part of the body of C2 (see
above). This ring may appear slightly incomplete
at its inferior and/or superior aspects—that is a
normal appearance. However, if either the
anterior or posterior margin of the ring appears
disrupted then a fracture through the base of the
Peg or the body of C2 is very possible and a C2
fracture will need to be excluded (p. 188).
Question 7. Check that the posterior arches of
C1 and C2 are intact.
Question 8.
Check that the vertebral bodies (C3–C7) are
intact.
The vertebral bodies below C2 have a fairly
uniform square or rectangular shape.
The anterior and posterior heights should be
approximately the same. The front to back widths
of all of the vertebrae are approximately similar.
Question 9. You can trace the three main
contour lines (arcs) as follows:
Line 1: along the anterior margins of the
vertebral bodies (anterior line).
Line 2: along the posterior margins of the
vertebral bodies (posterior line).
Line 3: along the bases of the spinous processes
(spinolaminar line).
Each line should be a smooth unbroken curve
or arc. No kink. No step. Trace these lines along
the full length of the cervical spine. Line 1
extends from the top of the anterior cortex of the
Peg to the anterior margin of the body of T1
vertebra.
Potential Pitfall: Line 3 will sometimes show a
slight step at the C2 level, particularly in
children8.
Apply this rule: this step should not be more
than 2 mm posterior to the smooth arc as it is
traced upwards between C3 and C1 vertebrae.
Question 10. Are the pre-vertebral soft tissue
shadows normal? The soft tissue shadow7,9–11
anterior to the vertebral bodies has a
characteristic configuration and width. Any bulge
or local increase in width indicates haemorrhage
and connotes an important injury.
NB: The absence of a bulge does not exclude a
ligamentous or bone injury. Indeed, even with a
major injury, a soft tissue bulge due to a
haematoma is fairly rare.
Maximum normal width of the
prevertebral soft tissues
Level
Width
Approximate % of a vertebral body (AP)
width
C1–C4
7 mm
30%
C5–C7
22
100%
mm
Priority 2: AP Peg view checklist
The anatomical arrangement of the C1–C2 articulation
allows extensive neck rotation whilst providing maximum
stability. This stability depends on the integrity of the
ligaments, particularly the C2 transverse ligament. Various
other ligaments enable C1 vertebra to be held in the
optimal position above the body of C2 vertebra. Any
deviation from this alignment indicates either ligamentous
disruption or a broken vertebra.
Ask yourself three important questions:
1. Do the lateral margins of C1 align vertically with the
adjacent lateral margins of C2?
2. Are the spaces on each side of the Peg approximately
equal?
3. Is there a fracture line across the base of the Peg?
Question 1.
We teach that a more relevant name for the Peg
view is:
“The lining up of the lateral masses view”.
Normal anatomy of the
Looking down from above.
C1–C2
articulation.
If the lateral masses do not align vertically, then
there could be several possible explanations.
First consider subluxation due to ligament
rupture.
Second, consider fracture of the body of C1;
either isolated to a single lateral mass or to a
burst fracture of C1 (a Jefferson fracture).
Finally, consider a developmental variation or just
simple rotation of a normal neck (see p. 182), as
shown on this AP Peg view.
Question 2: Frequent pitfall.
Slight rotation of the neck may cause the space
on each side of the Peg to appear unequal.
However, if the lateral masses of C1 and C2
remain normally aligned then the asymmetry can
be attributed to rotation rather than indicating
damage to the transverse ligament (p. 191).
Question 2: Pitfall.
Occasionally, asymmetric alignment of a lateral
mass will be present; ie the edges of the adjacent
C1/C2 lateral masses do not line up perfectly.
This might suggest vertebral subluxation.
However, non-pathological causes for this finding
do occur: either some slight positional rotation of
the neck, or a developmental variation in the size
of the C1 and C2 lateral masses1,12–14. In most
instances it is fairly easy to decide whether an
offset on one side of the C1–C2 articulation is
simply developmental… just check whether there
is any offset on the other side. If the lateral
masses line up normally on the other side then
developmental
asymmetry
is
the
likely
explanation.
Question 3: Pitfall—the Mach effect.
It is very common to see a thin black line crossing
the base of the Peg or the top of the Peg. This is
an
optical
illusion15
resulting
from
the
overlapping shadows of superimposed structures.
This line is known as a Mach band or a Mach
effect. Be aware of this line.
But, be careful…
The inexperienced observer should always seek
advice before too readily dismissing any line in
this area as a Mach artefact.
Another artefact.
The apparent vertical fracture through the Peg is
an artefact. It is caused by the gap between two
of the teeth (incisors).
Priority 3: Long AP view checklist
The lateral and Peg views are the most useful images. The
diagnostic return from the long AP view, in terms of
abnormalities detected, will be considerably less. In
addition, it is easy for the unwary to read too much into the
AP view.
Ask yourself two questions:
1. Are the spinous processes in a straight line?
If not, consider unilateral facet joint dislocation (see p.
194).
2. Is the space between adjacent spinous processes
approximately equal?
A warning: if a space is more than 50% wider than the
space immediately above or below, this is highly suggestive
of an anterior cervical dislocation16. In practice this
observation is most useful in the severely injured patient
whose shoulders have obscured some of the vertebrae on
the lateral radiograph17. It can provide an important
warning that the neck must be managed very carefully until
a lateral view or CT has accurately defined the alignment of
the vertebrae.
The normal radiograph shows the spinous
processes in a straight line.
The C4 and C5 spinous processes are bifid and
bifid processes are a very common occurrence.
The drawings illustrate how an anterior
dislocation can result in a large gap between the
spinous processes at the affected level.
Question 1: Pitfall.
Sometimes a bifid spinous process (a normal
variant) might suggest that the processes are not
in a straight line.
This normal radiograph shows bifid processes
at all levels.
Question 2: Pitfall.
If muscle spasm causes the neck to be held in
flexion then the 50% rule does not apply.
Whenever the 50% rule (p. 184) is broken you
must check the lateral view again in order to see
whether or not neck flexion or a dislocation is the
explanation for the increase in space on the AP
radiograph.
The common injuries
Injuries at C1
The C1 (Atlas) vertebra is a vulnerable
structure.
(a) Normal appearances of the C1–C2 articulation
on the AP Peg view and on the lateral view.
(b) C1 is a thin and insubstantial bone (rather like
a Polo mint or a Life Saver).
(c) A vertical (ie axial) force can shatter this Polo
mint. Examples include: a heavy weight falling
on the top of the head; the skull hitting the
bottom of an empty swimming pool.
(d) A vertical force can fracture C1 in several
positions (a Jefferson fracture). Sometimes the
transverse ligament (situated across the
posterior aspect of the odontoid peg) can
rupture. On occasion high impact forces (not
necessarily vertical) will cause the transverse
ligament to rupture on its own.
Jefferson fracture: C1 vertebra
(a) A normal C1 vertebra viewed from above.
(b) A vertical (axial) force has shattered the C1
vertebra and caused a rupture of the transverse
ligament.
(c) The appearance of (b) as it would be seen on
an AP Peg view. The main finding is the
displacement of the C1 lateral masses on the
right side—ie they do not line up with the lateral
masses of the C2 vertebra. The fracture lines
might not be easy to identify.
(d) Radiograph of a patient struck on the top of
the head by a violent vertical force. There is a
unilateral (left-sided) Jefferson fracture. This
Peg view shows that the lateral masses of C1
and C2 on the patient's left side do not line up.
Also, there is fragmentation of the left lateral
mass of the C1 vertebra. The CT scan (e)
confirms these findings (and also shows an
additional undisplaced fracture of the C2
vertebra).
Injuries at C2 involving the Peg
Evidence from the lateral view
▪ A line (fracture) crossing the Peg. Usually seen across its
base.
▪ Any misalignment in the anterior or posterior cortex of
C2.
▪ Any break in the anterior or the posterior margin of
Harris' ring (p. 176).
Top images: Fracture of the Peg. Posterior
displacement of the body of C2 vertebra.
Bottom image: Fracture of the Peg. Anterior
displacement of the body of C2 vertebra.
The key to diagnosis is understanding the
normal anatomy.
Confused? Start by identifying the anterior arch
of the C1 vertebra (ie the “coffee bean”, p. 175).
The coffee bean is an easily identifiable landmark
that is present on all radiographs. The normal
Peg should be positioned immediately behind the
coffee bean. The anterior aspect of the normal
Peg should continue inferiorly as the anterior
cortex of the body of C2 vertebra.
Evidence from the Peg view
▪ A line crossing the base of the Peg (beware Mach band
artefacts, p. 183).
▪ A Peg that is not vertical (ie it is tilted to the left or to the
right).
▪ In practice the AP Peg view rarely discloses a Peg
fracture easily—the lateral radiograph is the crucial view
to rely on.
A base of Peg fracture.
Often very difficult to diagnose on the AP Peg
view.
Sometimes a fractured Peg will lean to one
side.
Apply this aphorism:
“A leaning Peg is a bad Peg”
Injuries involving the body or the
posterior elements of C2
C2 Hangman's fracture8.
A
bilateral
fracture
through
the
pars
interarticularis of C2 vertebra. Unstable injury
caused
by
hyperextension.
Historically
consequent on hanging. Now typically results
from a motor vehicle accident with (eg) the
forehead striking the dashboard. In this patient
there is also a fracture of the body of C3.
Oblique fracture through the body of
the C2 vertebra.
Sometimes this causes the anterior-posterior
width of the body of C2 to be increased18 (the socalled “Fat C2“ sign).
C2
Hangman's
fracture
with
displacement of C2 on C3 vertebra.
anterior
C2 subluxation due to rupture of the
transverse ligament
The transverse ligament viewed from above. (a)
= normal, (b) = ruptured.
Ruptured ligament: Evidence from the Peg
view. Check the margins of the lateral masses of
C1 and C2. If all four lateral masses do not line
up in a normal manner then a rupture of the
ligament is probable. A Jefferson fracture (p. 186)
is an alternative possibility.
Ruptured ligament: Evidence from the
lateral view.
The space between the anterior arch of C1 (the
“coffee bean”) and the anterior aspect of the Peg
must not exceed 3 mm in adults.
In this patient the space is approximately 7 mm.
C2 has subluxed posteriorly because the
transverse ligament has ruptured.
Fractures C3–C7
Including spinous process fracture, vertebral body
compression fracture, and hyperflexion teardrop fracture.
The cardinal rule: The lateral radiograph must always,
always, include a well visualised superior surface of the T1
vertebra. Many errors1,3,5 occur because the top of T1 has
not been included on the radiograph. Check the lateral
view as described on p. 174.
C7 spinous process fracture. This is evidence
of major violence. Important ligaments are likely
to be torn.
C7 vertebral body compression fracture
(arrow). Consequent on a flexion injury.
C6 hyperflexion teardrop fracture.
Consequent on extreme flexion and axial loading.
An unstable injury.
Subluxations/dislocations C3–C7
Anterior subluxation.
A flexion-rotation injury. Recognition is usually
easy. Detected when there is disruption—at any
level—of the three arcs described on page 178.
Sometimes it is a single arc that appears most out
of line.
Subluxed mid-cervical vertebra with arc
disruption.
Unilateral facet joint dislocation.
Consequent on a distraction–flexion force with a
rotational element. Commonly overlooked on
radiographs.
Look for:
▪ AP view: spinous processes out of line.
▪ Lateral view: 10–20% forward subluxation (at
the C6/C7 level in this patient).
Then:
▪ Obtain the opinion of an experienced observer.
▪ Confirmation of this very precise diagnosis
requires the judgement of an expert.
Explaining unilateral facet joint
dislocation
The facet of one vertebra has jumped forwards
off the facet of the vertebra below. The jump
occurs on one side only.
The rotational displacement at the facet joint
causes the spinous processes to be out of line on
the AP view.
The jumping off of one facet (arrow) from the
facet below (arrowhead) results in the forward
subluxation on the lateral view.
Pitfalls
On the AP Peg view
▪ An unequal space on each side of the Peg is commonly
due to patient positioning with the neck slightly rotated.
All the same, such a finding necessitates very careful
inspection of the alignment of the lateral masses (see p.
180).
▪ A black line across the Peg might be a Mach effect or
tooth artefact (p. 183) rather than a fracture. Evaluation
of the lateral view is then the important next step.
On the long AP view
▪ A bifid spinous process may falsely suggest that
processes are not in line(pp. 184–185).
▪ If muscle spasm holds the neck in flexion, the 50% rule
for normal spacing does not apply (pp. 184–185).
Developmental variants
A vertebra (arrow) may appear slightly narrow
anteriorly with loss of the normal square or
rectangular
outline.
This
can
mimic
a
compression fracture.
Sometimes this narrowed appearance is due to
old trauma. Occasionally it is due to persistence
of the normal but slightly wedged shape that is
often present during adolescence19.
Anterior opacity
A small calcified opacity anterior to a vertebral
body can be mistaken for an avulsed fracture
fragment. Sometimes it is simply a remnant of an
old secondary ossification centre19 (left). An age
related osteophyte can also produce a similar
appearance (right). When such an opacity is
detected, an experienced observer should review
the radiographs.
Spasm related—delayed instability
Following trauma, severe pain and spasm may make it
difficult to exclude a significant injury to the posterior
ligament complex. Muscle spasm can hold the neck in an
anatomical position and mask ligamentous rupture.
Instability may only become evident after a few days when
the spasm has reduced.
It is therefore important that any patient with severe pain
and spasm who appears fit for discharge and is put in a
collar should be asked to attend again in a few days for
further evaluation. Lateral views in flexion and extension
might form part of that evaluation. These additional
radiographs must be taken under close clinical supervision.
If they remain at all equivocal, an MRI examination should
be obtained in order to exclude a ligamentous injury.
Age related changes
Age related degenerative changes are very common over
the age of 40. Distinguishing between changes due to
cervical spondylosis and those resulting from an acute
injury is not always easy.
The age related appearances shown below are frequently
present in the middle-aged and the elderly.
Anterior subluxation of a vertebra secondary to
facet joint degenerative change (at several levels
on this radiograph). There is no simple way of
distinguishing this from traumatic subluxation. In
most cases, correlation of the clinical symptoms
and signs with the site of the radiographic
abnormality will provide reassurance. In some
cases an injury should be assumed until an
experienced
observer
has
reviewed
the
20
radiographs .
A step in the anterior vertebral line. The step is
due to a protruding anterior osteophyte. It might
be misinterpreted as indicating vertebral
subluxation.
References
1. Richards PJ. Cervical spine clearance: a review.
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in comatose trauma patients: a pilot prospective
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3. Daffner RH, Sciulli RL, Rodriguez A, et al. Imaging
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Distribution and patterns of blunt traumatic cervical
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imaging diagnosis of cervical spine injury in the very
elderly: implications of the epidemiology of injury.
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7. Harris JH, Burke JT, Ray RD, et al. Low (type III)
odontoid fractures: a new radiographic sign.
Radiology. 1984;153:353–356.
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cervical spine trauma. 3rd ed. Williams & Wilkins;
1996.
9. Harris JH. The cervicocranium: its radiographic
assessment. Radiology. 2001;218:337–351.
10. Herr CH, Ball PA, Sargent SK, Quinton HB.
Sensitivity of prevertebral soft tissue measurement
at C3 for detection of cervical spine fractures and
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11. Matar LD, Doyle AJ. Prevertebral soft-tissue
measurements in cervical spine injury. Austr Radiol.
1997;41:229–237.
12. Gehweiler JA Jr, Daffner RH, Roberts L Jr.
Malformations of the atlas vertebra simulating the
Jefferson fracture. Am J Roentgenol. 1983;140:1083–
1086.
13. Suss RA, Zimmerman RD, Leeds NE. Pseudospread
of the atlas: false sign of Jefferson fracture in young
children. Am J Roentgenol. 1983;140:1079–1082.
14. Mirvis SE. How much lateral atlantodental interval
asymmetry and atlantoaxial lateral mass asymmetry
is acceptable on an open-mouth odontoid
radiograph. and when is additional investigation
necessary? Am J Roentgenol. 1998;170:1106–1107.
15. Daffner RH. Pseudofracture of the dens: Mach
bands. Am J Roentgenol. 1977;128:607–612.
16. Naidich JB, Naidich TP, Garfein C, et al. The
widened interspinous distance: a useful sign of
anterior cervical dislocation in the supine frontal
projection. Radiology. 1977;123:113–116.
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tissue injuries of the cervical spine. Curr Prob Diagn
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12
Thoracic & lumbar spine
Normal anatomy
Lateral view—thoracic and lumbar vertebrae 200
The three column spine 200
AP view—thoracic vertebrae 201
AP view—lumbar vertebrae 201
Analysis: the checklists
On the lateral view 202
On the AP view 204
The common injury
Vertebral fracture 206
Less frequent but important injuries
Fractures following trauma 207
Pitfalls
The right paraspinal line 211
Dismissing transverse process fractures as trivial
211
Schmorl's nodes 211
Regularly overlooked injuries
▪ Transverse process fractures.
The standard radiographs
Lateral and AP views.
Abbreviations
AP, anterior-posterior; L1, the 1st
vertebra; T6, the 6th thoracic vertebra.
lumbar
Normal anatomy
Lateral view—thoracic and lumbar
vertebrae 1–4
▪ The vertical contour of the lumbar spine is a
smooth unbroken arc.
▪ The vertebral bodies are the same height
anteriorly and posteriorly.
▪ The posterior margin of each vertebral body is
slightly concave.
▪ Each vertebra is intact—ie no step, no break, no
kinking.
The three column spine
The concept of a three column spine1 is a familiar
one when evaluating a CT or MRI examination.
This anatomical concept can also be applied to
the lateral radiograph.
▪ Anterior column The anterior longitudinal
ligament, the anterior part of the annulus
fibrosus, and the anterior two thirds of the
vertebral body.
▪ Middle column The posterior longitudinal
ligament, the posterior part of the annulus
fibrosus, and the posterior margin of the
vertebral body.
▪ Posterior column The facet joints, the
pedicles, and the posterior ligaments.
AP view—thoracic vertebrae
In the thoracic spine the soft tissue shadow of the
left paraspinal line (aka paravertebral stripe)
should be closely applied to the vertebral bodies.
This line is produced by the interface between the
paravertebral soft tissues and the adjacent lung.
On the right side there is no visible paraspinal
line5,6.
AP view—lumbar vertebrae
In the lumbar region the pedicles should become
gradually wider apart when descending from L1
to L5.
In the lumbar spine there is no visible
paraspinal line.
Analysis: the checklists
▪ A step-by-step analytical approach when evaluating the
plain films may provide an immediate indication that a
potentially catastrophic injury has occurred.
▪ The AP projection can provide useful information, but the
lateral radiograph is invariably the more useful. 70–90% of
detectable plain film abnormalities will be shown on the
lateral projection7,8. Also, it is the lateral radiograph to
which the three column stability principle1–3 is applied:
“Instability is present if any two of the three columns are
disrupted”
On the lateral view
Look for:
▪ Loss of height or wedging of a vertebral body: this is
evidence of a compression fracture. Wedging may be
associated with loss of the normal concavity of the
posterior aspect of the vertebral body9. This loss indicates
significant posterior displacement of the middle column.
▪ Fragment(s) of bone detached from the anterior aspect of
a vertebral body.
▪ More than one abnormality. The importance of
recognising all of the radiological abnormalities that may
be present is explained under stability (pp. 209–210).
Wedge compression
vertebra.
fracture
of
a
lumbar
L1 wedge compression fracture.
Wedge compression fractures.
▪ Top left: two fragments have been detached.
Two columns are disrupted… the anterior and
middle columns. Unstable.
▪ Top right: Several fragments. The posterior
margin of L1 is disrupted and bulges into the
spinal canal. Two column disruption. Unstable.
▪ Bottom left and right: Large fragment in canal.
Two columns disrupted. Unstable.
On the AP view
Thoracic spine
Look for:
▪ Localised displacement or widening of the thoracic
paraspinal lines. In the context of trauma, displacement or
bulging should be regarded as indicating a paraspinal
haematoma resulting from a vertebral body fracture.
Thoracic and/or lumbar spine
Look for:
▪ Abnormal widening of the distance between the pedicles.
This indicates that vertebral fragments have splayed
apart.
▪ Fracture of a transverse process. This can be subtle;
careful windowing on the digital images will usually be
necessary.
The image on the left is normal. Note that the
left paraspinal line (arrowheads) parallels the
lateral margin of the vertebral bodies. Further
laterally, is the vertical shadow of the descending
aorta.
The image on the right is abnormal. There is a
bulge of the left paraspinal line (arrowheads)
caused by a haematoma resulting from the
fracture of T6 vertebra. The haematoma has
caused the right paravertebral stripe to appear as
a bulge (arrows) in this patient. Normally, the
right paravertebral stripe is not visible.
Left: T12 fracture. The vertebra has lost height.
Note that the pedicles have been splayed apart.
Right: fracture of a lumbar vertebra. The pedicles
have been splayed apart. Normally, the pedicles
gradually splay apart very slightly from L1 to L5,
but there should not be any sudden widening as
shown here.
Fractures
of
the
right-sided
transverse
processes of L2, L3, and L4 vertebrae (arrows).
Most commonly these fractures result from
rotation or extreme lateral bending.
Helpful hint: In the context of high energy
trauma (and multiple injuries) the detection of
transverse process fractures should raise the
possibility of a major injury lower in the
lumbosacral spine. See “sentinel sign”, p. 211.
The common injury
There is only one common—ie regularly occurring—
vertebral fracture.
Osteoporotic compression fractures10.
□ Vertebral compression fractures are common in an
ageing population.
□ Many/most of these fractures are clinically silent.
Approximately 30% of people sustaining a fracture will be
symptomatic and usually present with back pain.
□ Radiologically the appearance on the lateral radiograph
is that of a wedge compression fracture.
Compression fracture of a mid thoracic
vertebra.
In this example a haematoma bulges the left
paravertebral stripe. In practice such a
haemorrhagic bulge is rare unless high energy
trauma has occurred.
Elderly patient with severe back pain.
Compression fractures (vertebral flattening) of
T11 and T12 vertebrae.
Less frequent but important injuries
Fractures following trauma
These important injuries are all consequent on high energy
trauma. The forces acting at the time of a particular injury
can be very complex.
Assessment:
▪ First, look for distinct fracture patterns.
▪ Second, assess stability by evaluating the three columns.
Distinct fracture patterns…
Flexion compression injury (wedge
fracture) of L2 vertebra.
Radiological pattern: The anterior aspect of the
vertebral body loses height, but the posterior part
does not.
Vertical compression injury (burst
fracture) of L1 vertebra.
Radiological pattern: Severe comminution and
flattening of a vertebral body. Often caused by a
fall from a height and landing on the feet.
Flexion/distraction injury (Chance-type)
fracture.
In this case of L3 vertebra.
Radiological pattern: This is a shearing
injury. Various patterns occur11,12.
One fairly common pattern: The vertebral
body fractures transversely, with the spinous
process and the postero-superior aspect of the
vertebral body also fractured. Classically a headon car crash with the upper torso hurled forwards
whilst the pelvis is held by a lap seat belt.
Fracture dislocation injury. In this case
affecting the T12/L1 level. (Additional vertebral
fractures are also evident.)
Radiological
pattern:
A
fracture
and
subluxation (or dislocation) of one vertebra on
another.
Assessing stability by evaluating the three
columns…
When a radiographic abnormality is detected it needs to be
categorised as showing either a stable or an unstable
appearance. Assess each of the three columns on the
lateral radiograph (p. 200). In general, the term ‘stable
injury’ should only be applied to minimal/moderate
compression fractures with an intact posterior column.
The three columns are normal in this
illustration. The alignment, the shape, and the
contours of these vertebrae are seen to be
anatomical. The assessment of each column on
every lateral radiograph is a most important task.
If a disruption of any two of the three columns is
detected then the injury will be classified as
unstable.
Instability is present if any two of the
three columns are disrupted.
Left: vertebral body fracture. Two columns are
disrupted. Unstable injury. Right: vertebral body
fracture. Two columns are disrupted. Unstable
injury.
Stability following high energy trauma
Wedge
fracture.
Many are stable. Nevertheless, the clinical
significance of a particular wedge fracture
may be underestimated. These fractures will
occasionally cause middle column bone
fragments to intrude into the spinal canal.
Burst
fracture
Invariably unstable.
Chance-type
fracture:
Unstable. Usually disrupted posterior and middle
columns; frequently, the anterior column is
also involved.
Fracture
dislocation
injury
Highly unstable.
Transverse
process
fracture
As an isolated finding this is a stable injury.
Pitfalls
The right paraspinal line
This line is situated adjacent to the thoracic vertebrae and
it is not seen in normal individuals. There is one exception:
it may be visualised in some middle-aged and elderly
patients because the pleura is displaced by age-related
lateral osteophytes13. In these patients the visible right
paraspinal line does not signify pathological tissue.
Dismissing transverse process
fractures as trivial
If transverse process fractures are seen after high energy
trauma. then it is important to assess the lumbosacral
junction appearances most carefully14. Following severe
high energy trauma transverse process fractures may be
overlooked, or dismissed as minor, particularly in the
presence of pulmonary, abdominal, vascular, or brain injury.
Lumbosacral junction dislocation (a rare injury) frequently
has fractures of several transverse processes on the AP
view. This has given rise to the term “sentinal sign”.
Schmorl's nodes14
These are focal indentations of the vertebral body end
plates seen at all ages but most commonly in younger
people. The aetiology of Schmorl's nodes is controversial
and their clinical importance remains undecided. They are
a relatively common finding in the thoracic and lumbar
spine. A Schmorl's node should not be read as an important
pathological finding.
Two patients with irregular indentations on the
end plates of several vertebral bodies. Schmorl's
nodes.
References
1. Denis F. The three column spine and its significance
in the classification of acute thoracolumbar spinal
injuries. Spine. 1983;8:817–831.
2. Murphey MD, Batnitzky S, Bramble JM. Diagnostic
imaging of spinal trauma. Radiol Clin North Am.
1989;27:855–872.
3. Pathria MN, Petersilge CA. Spinal trauma. Radiol
Clin North Am. 1991;29:847–865.
4. Vialle R, Charosky S, Rillardon L, et al. Traumatic
dislocation of the lumbosacral junction diagnosis,
anatomical classification and surgical strategy.
Injury. 2007;38:169–181.
5. Genereux GP. The posterior pleural reflections. Am J
Roentgenol. 1983;141:141–149.
6. Donnelly LF, Frush DP, Zheng J, et al. Differentiating
normal from abnormal inferior thoracic
paravertebral soft tissues on chest radiography in
children. Am J Roentgenol. 2000;175:477–483.
7. Berquist TH. Imaging of orthopedic trauma. 2nd ed.
Lippincott Williams & Wilkins; 1992.
8. Gehweiler JA, Osborne RL, Becker RF. The radiology
of vertebral trauma. WB Saunders; 1980.
9. Daffner RH, Deeb ZL, Rothfus WE. The posterior
vertebral body line: importance in the detection of
burst fractures. Am J Roentgenol. 1987;148:93–96.
10. Prather H, Watson JO, Gilula LA. Nonoperative
management of osteoporotic vertebral compression
fractures. Injury. 2007;38(3):S40–S48.
11. Bernstein MP, Mirvis SE, Shanmuganathan K.
Chance-type fractures of the thoracolumbar spine:
imaging analysis in 53 patients. Am J Roentgenol.
2006;187:859–868.
12. Groves CJ, Cassar-Pullicino VN, Tins BJ, et al.
Chance-type flexion-distraction injuries in the
thoracolumbar spine: MR imaging characteristics.
Radiology. 2005;236:601–608.
13. de Lacey G, Morley S, Berman L. The Chest X-Ray: A
Survival Guide. Elsevier; 2008.
14. Pfirrmann CW, Resnick D. Schmorl nodes of the
thoracic and lumbar spine: radiographic-pathologic
study of prevalence, characterization, and
correlation with degenerative changes of 1,650
spinal levels in 100 cadavers. Radiology.
2001;219:368–374.
13
Pelvis
Normal anatomy
Normal AP view 214
Developing skeleton: Synchondroses 214
Developing skeleton: Pelvic bone apophyses 215
Analysis: the checklist
The AP radiograph 216
Common fractures, high-energy
Fractures involving the main bone ring 218
Acetabular fractures 219
Sacral fractures 220
Common fractures, low-energy
Simple fall in the elderly 222
Injury to the coccyx 222
Apophyseal avulsion in the young 222
Sports injuries
Specific sports-related avulsions 224
Pitfalls
In adults and in children 225
Regularly overlooked injuries
▪ Undisplaced acetabular fracture.
▪ Detached acetabular fragment in a patient with
a dislocated hip.
▪ Sacral fractures.
▪ Avulsed apophysis from the proximal femur or
from the innominate bone.
The standard radiograph
AP view.
Abbreviations
AIIS, anterior inferior iliac spine; AP, anteriorposterior; ASIS, anterior superior iliac spine;
RTA, road traffic accident; SI joint, sacro-iliac
joint.
Normal anatomy
Normal AP view
The pelvis comprises three bone rings:
▪ The main pelvic ring
▪ Two smaller rings formed by the pubic and ischial bones
The robust sacro-iliac joints and the pubic symphysis are
part of the main bone ring. The sacro-iliac joints are the
strongest joints in the body and resist the normal vertical
and anterior-posterior displacement forces; the pubic
symphysis is the weakest link in the pelvic ring1–4.
Arcuate lines are visible as smooth curved borders on the
radiograph. They outline the roofs of the sacral formina.
Developing skeleton: Synchondroses
In children the synchondrosis (cartilaginous junction)
between each ischial and pubic bone can sometimes appear
confusing. In early childhood these unfused junctions may
simulate fracture lines. Subsequently, between the ages of
five and seven years, they may mimic healing fractures.
Developing skeleton: Pelvic bone
apophyses5–7
In adolescents and young adults the pelvis shows several
small secondary centres (the apophyses). These should be
radiographically identical on the two sides.
Apophyses are secondary centres that contribute to the
eventual shape, size, and contour of the bone but not to its
length. These centres are traction epiphyses as muscles
originate from or insert into them. They are vulnerable to
severe and acute muscle contraction, and also to repetitive
forceful muscle pulls when jumping, hurdling, turning
suddenly, or—occasionally—when dancing.
Each apophysis has a physis. The physis
(growth plate) is a particularly weak part of the
developing skeleton.
Age of appearance and fusion of apophyses at the
hip and pelvis (years)5,7
Apophysis
First seen on radiograph Fuses to skeleton
Innominate bone
AIIS
13–15
16–18
ASIS
13–15
21–25
Ischial tuberosity
13–15
20–25
Iliac crest
13–15
21–25
11–12
16–17
Femur
Lesser trochanter
Greater trochanter 2–3
16–17
Note that some apophyses remain unfused and normal, but are still vulnerable
into the early 20s, well after the growth of the long bones has been completed.
Analysis: the checklist
The AP radiograph
Assess:
1. The main pelvic ring. Scrutinise both the inner and outer
contours.
2. The two small rings forming the obturator foramina.
3. The sacro-iliac joints. The widths should be equal.
4. The symphysis pubis. The superior surfaces of the body
of each pubic bone should align. The maximum width of
the joint should be no more than 5 mm.
5. The sacral foramina. Disruption of any of the smooth
arcuate lines indicates a sacral fracture. Compare these
arcs on the injured and uninjured sides.
6. The region of the acetabulum. This is a complex area and
fractures at this site are easy to overlook3,8–10. Compare
the injured with the uninjured side.
In adolescents and young adults presenting with hip pain
but no history of a violent blow also assess:
7. The apophyses (p. 215).
Normal sacro-iliac joints.
Widths approximately equal. The inferior margin
of the iliac bone lines up with the inferior aspect
of the sacral part of the joint—on both sides.
Normal symphysis pubis.
No widening; superior margins at about the same
level.
Normal sacral foramina.
The roof of each sacral foramen has a smooth
arching superior margin (arrows). No break, no
ridge, no irregularity.
Assessing the apophyses.
Normal. The important finding is that both sides
of the pelvis, and both femora, are virtually
identical in appearance.There is no significant
difference at any site…particularly in the region
of each ASIS and AIIS (p. 215).
Common fractures, high energy
Fractures involving the main bone
ring
A double break in the main pelvic ring is an unstable injury.
Left: Fracture iliac bone and both pubic rami.
Unstable pelvis.
Centre: Bones intact. Ruptured sacro-iliac (SI)
joint and diastasis of the pubic symphysis.
Unstable pelvis.
Right: Ruptured SI joint and fractures of the
pubic rami. Unstable pelvis.
RTA. Note the following fractures: oblique
across the right iliac bone; right superior and
inferior pubic rami; left superior and inferior
pubic rami; body of the left pubic bone. Also, the
left SI joint is suspiciously wide. Highly unstable
injury.
A fracture at one site in a ring is likely to be
associated with a disruption of the ring at a
second site. The second break might be another
fracture or it might be ligamentous disruption at
the symphysis pubis (left) or at a SI joint (right).
Acetabular fractures9,10
▪ Frequently sustained by the driver or front seat
passenger in a road traffic accident. The patient may
complain of pain in the knee as well as in the pelvis.
▪ A posterior wall fracture is the most frequent acetabular
injury.
▪ Look through the femoral head for evidence of a subtle
fracture of the acetabulum.Careful scrutiny is essential.
The fracture is frequently comminuted and bone
fragments may be trapped within the joint.
▪ Bone fragments are clinically important. If undetected the
consequences may be either difficulty in reduction or
premature degenerative change.
An acetabular fracture (arrow) may result from
direct trauma (left) or be associated with a
posterior dislocation of the hip (right).
Sacral fractures1,11
Often very difficult to detect. The arcuate lines of the sacral
foramina need to be carefully assessed, comparing one side
with the other.
These fractures are overlooked in as many as 70% of
cases. Many sacral fractures are undisplaced, and
overlying bowel gas can also obscure these fractures.
Additionally, other injuries are often present and these can
distract the unwary so that the sacrum is initially
overlooked.
A lateral compression force can cause a vertical
compression fracture of the sacrum together with
accompanying oblique fractures of the pubic rami.
RTA. High energy trauma. Note: diastasis
(widening) of the pubic symphysis, fracture of the
left superior pubic ramus and an undisplaced
fracture through the right acetabulum (arrow).
Unless looked for carefully, it is easy to overlook
the central fracture through the sacrum
(arrowheads); it extends inferiorly from the first
sacral segment.
Reminder: the normal sacrum.
The roof of each foramen (arrows) is smooth—no
step, no irregularity.
These smooth curved roofs are often termed
the “arcuate lines”.
Sacral fractures. Left: Fracture involving the
roof of the most superior sacral foramen (arrow)
on the left side. Also, a subtle, undisplaced,
fracture of the left acetabulum. Right: The roofs
of several foramina on the right side are stepped
and irregular (arrowheads).
Common fractures, low energy
Simple fall in the elderly
Fracture of a pubic ramus or pubic rami. A single fracture
of the superior pubic ramus is the commonest pelvic
fracture following a fall.
Solitary fracture of the superior pubic ramus
(arrow).
Fractures of the superior and inferior pubic
rami (arrows).
Injury to the coccyx
History: Fell on buttocks and the coccyx is tender. In
practice the radiograph of a normal coccyx may appear
angulated and very abnormal. In any case, the radiographic
findings do not affect management. Radiography is
unnecessary.
Apophyseal avulsion in the young5,7,12
These fractures are most commonly caused by repeated or
sudden muscle contraction. Avulsions occur during or just
after adolescence and not during childhood. Some
avulsions can occur during the early 20s when fusion to the
main skeleton has yet to occur (see p. 215). Very
occasionally a direct blow to an apophysis rather than
muscle contraction is the cause of the injury.
Recognition of an apophyseal injury on the plain
radiograph will help to avoid additional unnecessary tests
and/or inappropriate treatment. Treatment of these injuries
is invariably conservative: rest and pain relief.
The most common sites5,7 of apophyseal avulsion are the
ischial tuberosity, the ASIS, the AIIS, and the iliac crest.
Avulsion of the AIIS apophysis.
Avulsion of the ASIS apophysis.
Sports injuries: specific avulsions5–7
The pelvic apophyses are particularly vulnerable during
numerous activities: eg soccer, American football,
gymnastics, dance, jumping… ie during any activity that
involves rapid acceleration or deceleration, or a sudden
change of direction.
An adductor muscle avulsive injury to the apophysis at
the pubic symphysis is fairly common in athletes.
Radiologically the pubis on the affected side is irregular,
and this can extend to involve the inferior pubic ramus.
Avulsion of the lesser trochanter apophysis can occur
during vigorous sports, and also when kicking.
“Hip Pointers” are contusions to the iliac crest.
Contusions alone do not show major radiographic changes.
Avulsion of the lateral part of this apophysis—or entire
displacement—has been reported6.
Sometimes, in an athletic individual, the radiograph will
show that more than one apophysis is injured.
History: young athlete with pain in the region of
the ischium or the symphysis.
Suspect an apophyseal injury.
▪ Ischium: insertion of the hamstrings (left).
▪ Symphysis: insertion of the hip adductors
(right).
Caution:
▪ Healing of an avulsion injury may produce considerable
ossification/calcification and local deformity. This could be
because of wide displacement of the avulsed apophysis or
because exuberant calcification is laid down. Do not
confuse the appearance with that of a tumour.
▪ Also, rarefaction of bone or a moth-eaten
appearance/lucency at an injured apophysis may be
misinterpreted as bone infection or a bone tumour7,13.
Healing AIIS avulsion. Profuse callus is present.
Avulsion of the right AIIS.
The site of the left AIIS appears very slightly
rarefied, suspicious of an injury to this apophysis
also.
Pitfalls
In adults: Sacral fracture or sacro-illiac joint disruption
may be hidden because of patient rotation or by overlying
bowel gas.
In children: A normal os acetabuli or an impingement
effect (see p. 226) may be misinterpreted as an acute
fracture fragment.
This small fragment of bone is a common
finding in children and also in some adults. It is
an unfused ossification centre … an os acetabuli.
See also p. 242.
The appearance of the lateral aspect of the
acetabulum is either an unfused ossification
centre (an os acetabuli variant) or an
impingement effect14. It does not represent an
acute fracture.
References
1. Solomon L, Warwick DJ, Nayagam S. Apley's system
of orthopaedics and fractures. CRC Press; 2010.
2. Dyer GS, Vrahas MS. Review of the pathophysiology
and acute management of haemorrhage in pelvic
fracture. Injury. 2006;37:602–613.
3. MacLeod M, Powell JN. Evaluation of pelvic
fractures: clinical and radiologic. Orthop Clin North
Am. 1997;28:299–319.
4. White CE, Hsu JR, Holcomb JB. Haemodynamically
unstable pelvic fractures. Injury. 2009;40:1023–
1030.
5. Anderson S. Lower extremity injuries in youth
sports. Pediatr Clin North Am. 2002;49:627–641.
6. Rossi F, Dragoni S. Acute avulsion fractures of the
pelvis in adolescent competitive athletes:
prevalence, location and sports distribution of 203
cases collected. Skeletal Radiol. 2001;30:127–131.
7. El-Khoury GY, Daniel WW, Kathol MH. Acute and
chronic avulsive injuries. Radiol Clin North Am.
1997;35:747–766.
8. Theumann NH, Verdon JP, Mouhsine E. Traumatic
injuries: imaging of pelvic fractures. Eur Radiol.
2002;12:1312–1330.
9. Young JW, Burgess AR, Brumback RJ, Poka A. Pelvic
fractures: value of plain radiography in early
assessment and management. Radiology.
1986;160:445–451.
10. Durkee NJ, Jacobson J, Jamadar D, et al.
Classification of common acetabular fractures:
radiographic and CT appearances. Am J Roentgenol.
2006;187:915–925.
11. Robles LA. Transverse sacral fractures: a review.
Spine J. 2009;9:60–69.
12. Sundar M, Carty H. Avulsion fractures of the pelvis
in children: a report of 32 fractures and their
outcome. Skeletal Radiol. 1994;23:85–90.
13. Brandser EA, El-Khoury GY, Kathol MH. Adolescent
hamstring avulsions that simulate tumors. Emerg
Radiol. 1995;2:273–278.
14. Martinez AE, Li SM, Ganz R, Beck M. Os acetabuli
in femoro-acetabular impingement: stress fracture
or unfused secondary ossification centre of the
acetabular rim? Hip Int. 2006;16:281–286.
14
Hip & proximal femur
Normal anatomy
AP view 228
Lateral view 228
Secondary centres (apophyses) 229
Analysis: the checklists
Applied to the specific clinical history 230
The common injuries
Elderly patient after a simple fall 232
Adolescent patient with acute hip pain 236
Uncommon but important injuries
Acetabular fracture 238
Dislocations 239
Pitfall
Os acetabuli 242
Regularly overlooked injuries
▪ Femoral neck fracture—minimally displaced.
▪ Femoral neck fracture—inadequate assessment
of the lateral radiograph.
▪ Pubic ramus fracture.
▪ Apophyseal injuries in the young.
The standard radiographs
AP of whole pelvis.
Lateral projection of the painful hip.
Abbreviations
AIIS, anterior inferior iliac spine;
ASIS, anterior superior iliac spine;
CT, computed tomography;
MRI, magnetic resonance imaging;
RTA, road traffic accident;
THR, total hip replacement.
Normal anatomy
AP view
Lateral view
AP and lateral views
The femoral neck should:
▪ Have a smooth and intact cortex—no buckle, no step, no
ridge.
▪ Not show any transverse areas of sclerosis.
The intertrochanteric region should:
▪ Have an appearance identical to the same area on the
opposite femur.
▪ Not show any black or lucent line crossing the
intertrochanteric bone nor any interruption in the cortical
margin of the greater trochanter.
Secondary centres (apophyses)
The femur and pelvis of an adolescent will show several
small secondary centres (the apophyses).
▪ These should be radiographically identical on the two
sides.
▪ An apophysis contributes to the eventual shape and
contour of the bone but not to its overall length. Muscles
originate from/insert into the apophyses.
▪ Each apophysis has a physis. The physis (ie the growth
plate) is a particularly weak part of the developing
skeleton.
Analysis: the checklists
Detailed inspection should focus on the specific clinical
history. Thus…
An elderly patient has suffered a simple fall
Check for:
▪ A black line—a displaced fracture—across the femoral
neck.
▪ A white line—impacted fracture—in the subcapital region.
▪ A fracture line through the subcapital region, through the
trochanteric region, or through the subtrochanteric
region.
▪ A fracture of a pubic ramus.
A few fractures are very difficult to detect. If the
radiographs appear superficially normal it is important to
check again and answer the following questions:
▪ Are the cortical margins of the femoral neck smooth and
continuous, or is there a slight step?
▪ Have I checked the lateral radiograph carefully?
An adolescent patient has acute/chronic pain
following athletic activity
Check that:
▪ The femoral apophyses are similar on the painful and
unaffected sides.
▪ Check the iliac apophyses.
Patient of any age who has sustained high
velocity trauma
Check all of the features described above and also check:
▪ The acetabulum: is it fractured?
▪ The femoral head: is it dislocated?
▪ For multiple fractures of the femur and/or the pelvis.
Hip pain in a young patient with no history of
recent trauma
▪ Age 4–10 years: consider Perthe's disease of the femoral
head.
▪ Around the age of puberty: consider slipped capital
femoral epiphysis.
▪ Age 13–25 years: assess all of the femoral and iliac
apophyses. Chronic repetitive stress can affect the
tendinous or muscle attachment at an apophysis and
produce soft tissue calcification or an apophyseal
irregularity.
Normal AP view. Injured right hip. The
radiographer centres the X-ray beam fairly low so
that the proximal shaft of the femur is included.
The injured and uninjured sides can be compared.
Normal lateral view. The same patient as
above. The two sites that must be checked are
the neck of the femur and the trochanteric
region. This peculiar projection might seem
anatomically counterintuitive—see explanation on
p. 228.
The common injuries
Elderly patient after a simple fall
Femoral neck fracture
The most common cause of an acute orthopaedic admission
in the elderly. A fall is not always a prerequisite. As the hip
twists (eg during a stumble) a rotational force can occur,
causing a fracture through osteoporotic bone.
Fractures of the femoral neck and proximal femur1,2
occur at characteristic sites. Approximately 50% of all hip
fractures are trochanteric3.
The radiographic findings enable a fracture of
the femoral neck to be classified as intracapsular
or extracapsular. This classification has a major
impact on determining the choice of surgical
treatment.
Intracapsular fractures risk compromising the
blood supply to the head of the femur. The vessels
passing through the capsule of the joint are
extremely vulnerable. Disturbance/interruption of
the capsular arteries increases the risk of nonunion or avascular necrosis of the femoral head.
The blood supply is not similarly affected with an
extracapsular fracture.
Approximately 95% of hip fractures are widely displaced
and easy to detect. A few are very difficult to detect. If the
radiographs appear superficially normal it is important to
check again and answer the following questions:
▪ Are the cortical margins of the femoral neck really
smooth and continuous?
▪ Is there a black (ie lucent) line crossing the femoral neck?
▪ Does a dense white line (impaction in a compression
fracture) cross the neck?
▪ Is there any angulation of the neck… compared with the
uninjured side?
▪ Have I checked the lateral radiograph carefully?
Approximately 1% of femoral neck fractures will be
undetectable on the initial radiographs1. If the radiographs
appear normal and there is strong clinical suspicion of a
fracture (eg pain on weight bearing) then referral for a
same day MRI, CT, or radionuclide examination is
indicated. MRI is the preferred investigation.
The fracture that is most frequently missed/overlooked is
an undisplaced intracapsular fracture2.
Subcapital fracture.
The white line (arrows) indicates impaction.
Subcapital fracture.
Abnormal angulation (arrow) of the femoral neck
is evident.
Subcapital fracture.
Evident on
(arrows).
both
the
AP
and
lateral
views
Extracapsular intertrochanteric
fracture.
This fracture is subtle on the AP view. It is clearly
shown (arrow) on the lateral radiograph.
Pubic ramus fracture
A fracture of a pubic ramus can mimic the symptoms and
signs of an undisplaced femoral neck fracture.
Helpful hint: following a simple fall it is rare for a
patient to sustain both a femoral neck fracture and a pubic
ramus fracture.
The pubic rami form a ring. Bone rings
frequently sustain fractures at two positions
(arrows) within the ring.
Always look for two fractures involving the
rami.
Sometimes there is only one fracture involving
the pubic ring. Indeed, the commonest pelvic
fracture following a fall in an elderly patient is an
isolated fracture of the superior pubic ramus.
Adolescent patient with acute hip
pain4,5
Apophyseal injuries (See also pp. 222–225)
Many of the conditions presenting as acute hip pain in this
age group are actually injuries to the pelvis. Always
consider an apophyseal injury in a young patient.
Avulsions occur most commonly in sports where a quick
burst movement or explosive action occurs. Until the
growth centre fuses to the underlying bone (at any time
between the ages of 16 and 25 years) an apophysis
represents a site of weakness and is vulnerable to forceful
muscle contraction. The sites most commonly affected are:
▪ anterior inferior iliac spine (AIIS)
▪ anterior superior iliac spine (ASIS)
▪ ischial tuberosity
▪ iliac crest.
Always evaluate the iliac apophyses as well as the upper
femoral apophyses.
Sometimes bone overgrowth/fragmentation/calcification
at the injured site might be initially misinterpreted as
indicating a tumour6.
Clinical impact guideline: treatment of an apophyseal
injury is invariably conservative and based on rest and pain
relief. Nevertheless, correct diagnosis is still important.
The apophyses and their attached muscles.
Normal pelvis and hips. Note the normal
apophyses in relation to each lesser trochanter.
Note the normal appearances at the ASIS
(arrows) and the AIIS (arrowheads) on both sides.
Pain in the hip. The AIIS (arrow) has been
avulsed.
Pain in the hip. Avulsion of an apophysis (lesser
trochanter).
Uncommon but important injuries
Acetabular fracture
▪ A fracture of the acetabulum may produce very similar
clinical features to those resulting from an undisplaced
fracture of the femoral neck.
▪ The majority of acetabular fractures result from high
energy trauma. Occasionally, a fracture will occur after a
simple fall in an individual with severe osteoporosis.
▪ These fractures are very easy to overlook. Careful
scrutiny is essential.
High energy trauma.
Acetabular fracture (arrow).
High energy trauma.
Acetabular fracture (arrow).
Dislocations7,8
These injuries result from high energy trauma.
Dislocations can be posterior, anterior, or
Approximately 80% are posterior.
Posterior dislocation.
central.
The extreme force is transmitted up the shaft of
the femur, typically in a driver or front seat
passenger involved in a road traffic accident
(RTA).
The AP view usually demonstrates the
dislocation very clearly. The lateral radiograph
will confirm the diagnosis.
Young male (RTA).
The femoral head is dislocated posteriorly.
A large fragment has been detached from the
acetabular margin and lies above the head of the
femur. Several other fractures also resulted from
the violent impact on this driver at the time of the
collision.
Fractures of the acetabular margin are
common complications of posterior
dislocation.
The incidence of an accompanying acetabular
fracture can be as high as 70%7. Accompanying
fractures of the femoral head or neck also occur.
An unrecognised acetabular fragment can
prevent reduction or result in instability if the
acetabular defect is large. In this patient, the
dislocation has been complicated by two
fragments detached from the acetabular margin.
The fragments are situated superiorly and
inferiorly.
Central dislocation of the head of the
femur with fracture of the acetabulum.
The description “central dislocation” is common
parlance for this finding. It is not a true
dislocation because the femoral head remains
within the socket… but it has been forced
through the medial wall and lies, in part, within
the pelvis.
Dislocation following total hip
replacement (THR).
Easy to recognise. Occurs much more commonly
following a THR for a femoral neck fracture than
after an elective THR for other indications9.
Most
dislocations
occur
in
the
early
postoperative period. Some will dislocate later
and attend the Emergency Department; some will
become recurrent dislocators.
The most basic requirement.
Your ability to detect subtle fractures involving
the hip and the adjacent pelvis depends upon
your awareness of the normal radiological
anatomy (pp. 228–229). Good understanding is
essential. This radiograph is normal.
Pitfall
Os acetabuli.
A small bone fragment/ossicle at the superior
margin of the acetabular rim is a common
finding. It might represent an unfused secondary
ossification centre (an os acetabuli), or a
fragment
due
to
femero-acetabular
10
impingement .
This ossicle/fragment is most unlikely to
represent an acute fracture.
A specialist orthopaedic assessment will
invariably distinguish between an unimportant
ossicle (an os acetabuli) and an impingement
fragment representing a longstanding injury.
See also p. 226.
References
1. Parker M, Johansen A. Hip fracture. BMJ.
2006;333:27–30.
2. Parker MJ. Missed hip fractures. Arch Emerg Med.
1992;9:23–27.
3. Michaelsson K, Weiderpass E, Farahmand BY, et al.
Differences in risk factor patterns between cervical
and trochanteric hip fractures. Swedish Hip
Fracture Study Group. Osteoporos Int. 1999;10:487–
494.
4. Anderson S. Lower extremity injuries in youth
sports. Ped Clin North Am. 2002;49:627–641.
5. Rossi F, Dragoni S. Acute avulsion fractures of the
pelvis in adolescent competitive athletes:
prevalence, location,and sports distribution of 203
cases collected. Skeletal Radiol. 2001;30:127–131.
6. Brandser EA, El-Koury GY, Kathol MH. Adolescent
hamstring avulsions that simulate tumours. Emerg
Radiol. 1995;2:273–278.
7. Hak DJ, Goulet JA. Severity of injuries associated
with traumatic hip dislocation as a result of motor
vehicle collisions. J Trauma. 1999;47:60–63.
8. Clegg TE, Roberts CS, Greene JW, Prather BA. Hip
dislocations – Epidemiology, treatment, and
outcomes. Injury. 2010;41:329–334.
9. Gregory RJ, Gibson MJ, Moran CG. Dislocation after
primary arthroplasty for subcapital fracture of the
hip. Wide range of movement is a risk factor. J Bone
Joint Surg Br. 1991;73:11–12.
10. Martinez AE, Li SM, Ganz R, Beck M. Os acetabuli
in femero-acetabular impingement: stress fracture
or unfused secondary ossification centre of the
acetabular rim? Hip Int. 2006;16:281–286.
15
Knee
Normal anatomy
AP view 244
Lateral view 245
Analysis: the checklists
The AP radiograph 246
The lateral radiograph 248
The common fractures
Tibial plateau 250
Through the body of the patella 254
Osteochondral: articular surface of the patella 255
Neck of fibula 256
Other 257
Small fragments around the knee
Cruciate ligament & Segond fracture 259
Infrequent but important injuries
Several 260
Pitfalls
Several 262
The standard radiographs
AP and Lateral.
Suspected patella fracture, but AP & lateral are
equivocal: Skyline view.
Occasionally, a Tunnel view to evaluate the
intercondylar area.
Regularly overlooked injuries
▪
▪
▪
▪
Plateau fracture.
Segond fracture.
Small fragments in the joint.
Vertical fracture of the patella1.
Abbreviations
ACL, anterior cruciate ligament;
AP, anteroposterior;
FFL, fat–fluid level;
LCL, lateral capsular ligament;
MCL, medial capsular ligament;
PCL, posterior cruciate ligament.
Normal anatomy
AP view
Lateral view
Normal position of the patella—a useful
rule:
On the lateral radiograph the distance from the
tibial tubercle (on the anterior aspect of the tibia)
to the lower pole of the patella should
approximate to the length of the patella itself
±20%. This rule is relevant to diagnosing a
rupture of the patellar tendon1–3.
Analysis: the checklists
The AP radiograph
Adults: a five-point checklist
Check:
1. The “intercondylar eminence” (ie the tibial spines) of the
tibia and the condylar surfaces of the femur.
2. The head and neck of the fibula.
3. The tibial plateau:
□ Each plateau should be smooth. No steps, no layering,
no disruptions.
□ The subchondral bone should not show any focal
increase in density.
□ A perpendicular line drawn at the most lateral margin
of the femoral condyle should not have more than 5
mm of the lateral margin of the tibial condyle outside
of it. A similar rule can be applied to the relationship
between the medial femoral condyle and the medial
tibial plateau.
4. The patella. Look through the superimposed femur.
5. Finally, check for any small fragments of bone—
anywhere at all.
Normal AP.
Tibial articular surfaces. Appear as an oval
on either side of the intercondylar eminence.
These ovals should be smooth without any steps
or layering.
In the normal knee a perpendicular line drawn at
the most lateral or medial margin of the femur
should have no more than 5 mm of adjacent tibia
outside of it. If this rule is broken suspect a
plateau fracture.
Children: an eight-point checklist
1–5 as for adults, but also check:
6. The growth plates of femur, tibia, and fibula. Is there an
epiphyseal fracture? (See pp. 14–17).
7. The cortex of the femur and tibia. Is there a Greenstick
or Torus fracture? (See pp. 18–19.)
8. The condylar surfaces of the femur. Is there an
osteochondral lesion/fracture? (See pp. 28–29.)
Normal AP.
The lateral radiograph
It is important to understand the normal and abnormal
appearance of the suprapatellar bursa—if abnormal, this
often suggests a fracture or ligament damage4–6.
Adults and children: a six-point checklist
Check:
1. For a joint effusion4–7. Present if the suprapatellar strip
exceeds 5 mm (see below).
2. For a fat–fluid level in the suprapatellar bursa… an intraarticular fracture.
3. The condylar surfaces of the femur. Are they smooth?
4. The patella. Is the articular surface smooth?
5. The position of the patella.
6. For any small fragments of bone—no matter how small.
Normal lateral.
A soft tissue band (the suprapatellar strip)
separates the prefemoral fat pad from the
suprapatellar fat pad. Normally its AP width is no
more than 5 mm4,7.
The normal suprapatellar strip is, in effect, an
undistended suprapatellar bursa.
Large effusion.
Note the marked differences compared with the
normal appearances on the page opposite.
The suprapatellar strip is markedly widened.
Effusion with a fat–fluid level.
In the Emergency Department the lateral view of
the knee is obtained with a horizontal X-ray beam
(conventionally referred to as a “HBL”). A fat–fluid
level occurs when fat (arrowheads) lies on top of
blood in the suprapatellar bursa. The fat has been
released from bone marrow and consequently the
fat–fluid level indicates an intra-articular
fracture7–9.
The common fractures
Tibial plateau fracture
Usually seen as a depression in the lateral plateau
following violent impaction by the lateral femoral condyle.
The so-called ‘car bumper’ or ‘fender’ fracture. Many, but
by no means all, are true car bumper injuries. Sports
injuries and falls at home are other frequent causes.
▪ Radiographic evidence of an impacted fracture may be
subtle. There are four features to look for (see pp. 252–
253). Sometimes only one or two will be present.
80% of tibial plateau fractures involve the
lateral plateau as a result of a severe valgus
stress combined with a violent compressive force
which drives the femoral condyle into the tibial
plateau.
Lateral plateau fractures are often associated
with significant damage to the medial collateral
ligament or to a cruciate ligament.
Injury to the medial plateau (arrow) from a
blow to the medial side of the joint.
Tibial plateau fracture—the four
features to look for
Feature (1). The normal plateau is smooth—
but this alters when the plateau is fractured. The
fractured plateau has an irregular surface or
becomes layered. Additionally, fracture lines may
extend inferiorly.\
Feature (2). An area of focal increase in
density below the plateau due to bone
compression causing an impaction. Lateral
plateau fracture.
Feature (3). Tibial margin displacement. Use
this rule: “a perpendicular line drawn at the most
lateral margin of the femur should not have more
than 5 mm of the adjacent margin of the tibia
beyond it”. Lateral plateau fracture.
Feature (4). On the lateral radiograph, in most
cases of a fracture involving a plateau there will
be a fat–fluid level8,9, as shown here.
Fracture through the body of the
patella
Usually caused by a direct blow. Vertical, horizontal and
comminuted fractures occur. A violent contraction of the
quadriceps can cause a transverse fracture in an athlete.
Horizontal (left) and
fractures of the patella.
comminuted
(right)
Caution: this fracture was not seen on the
standard views of the knee. Occasionally this
occurs, usually with an undisplaced vertical
fracture. Clinical concern will determine whether
an additional projection is necessary1,7.
This is a skyline view.
Osteochondral fracture: articular
surface of the patella
Often consequent on high energy trauma in young patients.
Articular surfaces shear against each other. The medial
surface of the patella is usually affected.
Shearing force as shown.
Sometimes the defect in the articular surface, or
a detached fragment (arrow), is only shown on a
skyline (ie tangential) view1,10.
Occasionally a shearing injury to the articular
surface of the lateral femoral condyle occurs at
the time of a transient dislocation of the patella.
This can cause a visible defect in the femur
and/or a small sliver of bone within the joint.
Neck of fibula fracture
Don't dismiss an isolated fracture too lightly. These
fractures of the fibula are often consequent on high energy
trauma. Damage to the collateral or cruciate ligaments
within the joint are well recognised associations.
Both of these patients show a fracture through
the neck of the fibula. In addition, each patient
had also sustained a severe ligamentous injury.
Osteochondritis dissecans of the
knee
Repetitive trauma may cause a defect in the articular
surface of the femur. Most commonly affecting the lateral
aspect of the medial femoral condyle. See pp. 28–29.
Supracondylar and intracondylar
fractures of the femur
Most commonly consequent on high energy trauma in the
young; typically a road traffic accident. These fractures
also occur in elderly patients with severe osteoporosis who
have fallen. Detecting the fracture on the radiographs is
straightforward.
Fracture/avulsion of the tibial spine
An avulsion fracture of the tibial spine (the intercondylar
eminence) indicates a cruciate ligament injury because this
area is the site of attachment of these ligaments.
Avulsion fractures (arrows) of the tibial spine.
Small fragments around the knee
Any small fragment is important. It will warn you that an
important soft tissue injury is likely.
Cruciate ligament injury11,12
The cruciate ligaments insert into the intercondylar region
(ie anteriorly and posteriorly) of the tibial plateau. A
rupture may be accompanied by avulsion of a small
fragment detached from the site of the ligament's insertion
into the tibia.
Insertion of the ACL and PCL, shown on this
intercondylar sagittal section.
PCL avulsion fracture.
If a tiny fragment (arrow) is identified close to the
tibial articular surface posteriorly then the PCL is
likely to have been injured.
ACL avulsion fracture.
If a tiny fragment of bone (arrow) is identified
close to the intercondylar eminence (ie the tibial
spine) this is invariably consequent on an
avulsion of the tibial attachment of the anterior
cruciate ligament. Occasionally, the detached
bone fragment may be lying loose and visible
elsewhere within the joint.
Cruciate ligament or meniscus injury
—Segond fracture11–14
A tear of the lateral capsular ligament may cause a cortical
avulsion where it is attached to the tibia. The tear is
consequent on forceful internal rotation and varus stress.
This cortical avulsion is termed a Segond fracture.
A Segond fracture has a strong association with a tear of
the anterior cruciate ligament (ACL) and/or a meniscal
injury. More than 75% of patients with a Segond fracture
have torn the ACL.
A Segond fracture is regarded as the most frequent
indirect sign of an ACL tear seen on a plain radiograph.
The lateral capsular ligament has pulled a
fragment away from the cortex of the tibia. This
detached fragment represents the Segond
fracture.
Some of the possible associated ligamentous
tears are illustrated.
LCL = lateral capsular ligament.
MCL = medial capsular ligament.
Segond fracture. The fracture fragment (arrow)
lies at the margin of the lateral tibial plateau just
below the joint line.
The avulsed fragment may be very tiny. Size
varies from 1 mm to 27 mm14.
A common dislocation
Patella dislocation 15,16
The knee joint is most vulnerable when the leg is extended.
It is then that the patella is least stable and most
vulnerable to an external force.
Fracture complication: in approximately 20% of
patients who have dislocated the patella there will be a
small sliver of bone detectable on the plain radiographs.
This fragment detaches from the patella or from the lateral
femoral articular surface as part of a shearing injury during
the dislocation.
With many patients, who have suffered a transient patella
dislocation and subsequently attend the Emergency
Department, the dislocation will already have reduced
spontaneously. In these patients it is wise to obtain a
patellar view (skyline view) as well as the standard knee
radiographs as this will increase the chances of detecting a
fragment that might have sheared off at the time of
dislocation.
Infrequent but important injuries
Epiphyseal growth plate fractures.
See pp. 14–15.
Maisonneuve fracture.
Fracture through the proximal fibula, and an
associated ankle fracture. See p. 284.
Stress fracture of the tibia.
The most common site for a stress fracture
around the knee is in the proximal tibia (arrows).
The stress fracture in this patient is fairly
typical—it appears as a sclerotic band.
Sometimes the band is accompanied by
periosteal new bone along the adjacent cortical
margin.
Rupture of the patellar tendon.
Most commonly the result of direct trauma. The
rupture is through the proximal part of the
tendon close to the inferior pole of the patella.
Identified on the lateral radiograph by a high
position of the patella (as above).
A high position? Apply this rule: in the normal
knee, the distance from the tibial tubercle to the
lower pole of the patella should not exceed the
length of the patella by more than 20% (see
below).
Pitfalls
The fabella. A common sesamoid bone in the
tendon of the lateral head of the gastrocnemius
muscle. Its posterior position is characteristic. Do
not confuse the fabella (arrow) with a fracture
fragment or a loose body.
Bipartite patella. The patella may develop
from
several
ossification
centres,
which
sometimes remain unfused in the adult. Two
unfused centres are most common. The smaller
centre is characteristically positioned in the
upper outer quadrant, and may mimic a fracture.
An ossification centre will have a well defined
sclerotic (corticated) edge and its margin will
match the contour of the adjacent bone.
Occasionally there are three unfused centres
(tripartite patella).
Pellegrini–Stieda lesion. Calcification (arrow)
adjacent to the medial epicondyle following a
previous sprain of the medial collateral ligament.
Do not mistake this lesion for a fracture
fragment.
Patella Alta.
A high patella position due to a developmental
elongation of the infrapatellar tendon. Do not
confuse with a patella tendon rupture. A Patella
Alta predisposes to patella subluxation.
A rough guide: “if the inferior pole of the
patella
is
situated
entirely
above
the
intercondylar notch of the femur then this is
consistent with a Patella Alta”.
The tibial tubercle and Osgood–
Schlatter's disease
Osgood-Schlatter's disease is a condition that
occurs most commonly in adolescent boys. It is
suspected to be a chronic avulsion injury
resulting from recurrent episodes of minor
trauma11,17.
A plain film diagnosis cannot be made with
absolute
certainty
because
the
normal
ossification centre can appear very fragmented,
irregular, or separate. This diagnosis is best made
on clinical history and examination.
Do not misinterpret a normal appearance. The
two examples shown here (arrows) are normal.
References
1. Capps GW, Hayes CW. Easily missed injuries around
the knee. Radiographics. 1994;14:1191–1210.
2. Insall J, Salvati E. Patella position in the normal
knee joint. Radiology. 1971;101:101–104.
3. Newberg A, Wales L. Radiographic diagnosis of
quadriceps tendon rupture. Radiology.
1977;125:367–371.
4. Hall FM. Radiographic diagnosis and accuracy in
knee joint effusions. Radiology. 1975;115:49–54.
5. Butt WP, Lederman H, Chuang S. Radiology of the
suprapatellar region. Clin Rad. 1983;34:511–522.
6. Fishwick NG, Learmouth DJ, Finlay DB. Knee
effusions, radiology and acute knee trauma. Br J
Radiol. 1994;67:934–937.
7. The Knee. Chan O. ABC of Emergency Radiology.
3rd ed. Wiley Blackwell; 2013.
8. Ferguson J, Knottenbelt JD. Lipohaemarthrosis in
knee trauma; an experience of 907 cases. Injury.
1994;25:311–312.
9. Lee JH, Weissman BN, Nikpoor N, et al.
Lipohemarthrosis of the knee: a review of recent
experiences. Radiology. 1989;173:189–191.
10. Rorabeck CH, Bobechko WP. Acute dislocation of the
patella with osteochondral fracture: a review of
eighteen cases. J Bone Joint Surg. 1976;58:237–240.
11. Gottsegen C, Eyer B, White E, et al. Avulsion
Fractures of the Knee: Imaging Findings and Clinical
Significance. RadioGraphics. 2008;28:1755–1770.
12. Delzell PB, Schils JP, Recht MP. Subtle fractures
about the knee: innocuous-appearing yet indicative
of significant internal derangement. Am J
Roentgenol. 1996;167:699–703.
13. Sferopoulos NK, Rafailidis D, Traios S,
Christoforides J. Avulsion fractures of the lateral
tibial condyle in children. Injury. 2006;37:57–60.
14. Goldman AB, Pavlov H, Rubenstein D. The Segond
fracture of the proximal tibia: a small avulsion that
reflects major ligamentous damage. Am J
Roentgenol. 1988;151:1163–1167.
15. Haas JP, Collins MS, Stuart MJ. The ”sliver sign”: a
specific radiographic sign of acute lateral patellar
dislocation. Skeletal Radiol. 2012;41:595–601.
16. Anderson S. Lower extremity injuries in youth
sports. Pediatr Clin North Am. 2002;49:627–641.
17. Rosenberg ZS, Kawelblum M, Cheung YY, et al.
Osgood–Schlatter lesion: fracture or tendinitis?
Scintigraphic, CT, and MR imaging features.
Radiology. 1992;185:853–858.
16
Ankle & hindfoot
Normal anatomy
Lateral view 266
AP mortice 268
Axial projection—calcaneum 269
Analysis: the checklists
AP mortice 270
Lateral view 272
Axial view 273
Common fractures/torn ligaments
The malleoli 274
Base of the 5th metatarsal 276
The calcaneum 277
Growth plate (Salter–Harris) fractures 280
Ligamentous injuries
Torn medial or lateral ligaments; tear of the
interosseous membrane 281
Infrequent but important injuries
Fractures of the talus 282
Maisonneuve fracture 284
Distal tibial fractures involving the articular surface
285
Complex Salter–Harris fractures 286
Infrequent calcaneal fractures; os trigonum fracture
288
Talar dislocations 289
Pitfalls
Calcaneum; accessory ossicles 290
Regularly overlooked injuries 1
Talus: talar dome osteochondral lesion; neck of
talus fracture; medial or lateral process fractures.
Calcaneum: acute fracture; stress fracture.
Syndesmotic widening (tear of tibiofibular
membrane).
Base of 5th metatarsal fracture.
The standard radiographs
Ankle: AP mortice (20° internal rotation) and
Lateral. Sometimes a Straight AP2.
Calcaneal injury: an additional Axial.
Abbreviations
AP, anterior-posterior; AVN, avascular necrosis;
CT, computed tomography; MT, metatarsal; RTA,
road traffic accident.
Normal anatomy
Lateral view—bones and joints
The lateral and medial malleoli can be identified. Helpful
hints to aid identification:
▪ The lateral malleolus extends more inferiorly than the
medial malleolus.
▪ The medial malleolus has a notch inferiorly.
The posterior lip (or tubercle) of the tibia, conventionally
and inaccurately referred to as the posterior malleolus, is
well shown.
The calcaneum and its sustentaculum tali are
demonstrated. Bohler's angle can be assessed for
normality.
The base of the 5th metatarsal is often included.
Lateral view—ligaments
Principal ligaments—medial.
Principal ligaments—lateral.
AP mortice
The mortice projection is obtained with slight (20°) internal
rotation so that the fibula does not overlap the talus.
The joint space should be of uniform width all the way
around. This space is well seen medially, it continues over
the superior aspect of the dome of the talus, on to the
lateral side of the joint.
The width of the joint space measures approximately 4
mm2.
The surface of the talar dome should be smooth, smooth,
smooth. No irregularity, no notching, no defect.
The lateral process (also known as the lateral tubercle) of
the talus is an important structure. The talocalcaneal
ligament attaches to this part of the bone.
A useful rule: the bones of the tibia and fibula should
always overlap on the mortice view. Any clear separation
between these two bones should lead you to question
whether the interosseous membrane is torn.
Axial projection—calcaneum
The posterior two thirds of the bone is well shown; the
anteriorly positioned sustentaculum tali is often not as well
visualised on the radiograph.
Analysis: the checklists1,3,4
AP mortice
Check the:
▪ Malleoli—fracture or … fractures?
▪ Tibiofibular interosseous membrane—any suggestion of a
rupture?
□ If normal, the tibia and fibula should show some
degree of overlap.
□ A measurement: the width of the space between the
distal tibia and fibula at a point 1.0 cm proximal to the
tibial articular surface should not exceed 6 mm5.
▪ Talus
□ Dome—smooth?
□ Medial and lateral processes (ie the tubercles, p. 268)
—any fragmentation?
▪ Joint width—does any part exceed the normal 4 mm3?
▪ Epiphyses and growth plates in children—normal? (see
pp. 15 and 280).
Normal features and measurements (ie rules of
thumb) relating to:
(1) the interosseous membrane, and (2) the
various articulations at the mortice joint.
Normal AP mortice view.
All of the checkpoints are normal.
Note that part of the fibula overlaps part of the
tibia. This is a characteristically normal
appearance on a mortice view.
Normal AP mortice view. A child.
The growth plates and
checkpoints are normal.
all
of
the
other
Lateral view
Check the:
▪ Tibia
□ Cortices—intact?
□ Articular surface—smooth?
▪ Fibula
□ Oblique fracture line?
▪ Talus
□ Neck—intact?
□ Articulation with the navicular bone—can you see a
normal joint?
▪ Calcaneum
□ Any fracture lines?
□ Bohler's angle—normal?
□ Anterior process—normal?
▪ 5th metatarsal
□ Fracture of the base?
Measuring Bohler's angle.
Draw a line from the highest point anteriorly to
the highest midpoint. Then draw a line from the
highest point posteriorly to the highest midpoint.
The angle subtended should be 30° or more.
Normal lateral.
Checkpoints: all normal.
Joints: all normal.
Bohler's angle: normal.
Base of 5th metatarsal: normal.
Axial view
Check the:
▪ Calcaneum.
□ Any fracture lines?
□ Cortices—intact?
The normal standing foot seen from behind.
This drawing may help you to understand the
anatomy on the axial view of the calcaneum. The
sustentaculum tali is the shelf-like part of the
calcaneum which extends medially to support
part of the head of the talus.
Normal axial view.
1 = Sustentaculum tali
2 = Posterior talocalcaneal joint
3 = Posterior body of calcaneum
Common fractures/torn ligaments
The malleoli 3,6
▪ Most ankle fractures involve one or both malleoli. These
fractures are often easy to diagnose because you will
know precisely which bones are tender.
▪ The direction of the applied forces will determine the
particular fracture (or fractures) and any associated
ligamentous damage:
□ In (a) below, abduction and external rotation forces.
□ In (b) below, adduction forces.
This illustration is adapted in modified form
from Tidy's Physiotherapy7.
Transverse fracture of the lateral malleolus.
Transverse fracture of the medial malleolus;
oblique and transverse fractures of the distal
fibula and lateral malleolus; lateral subluxation of
talus.
Multiple fractures affect the tibia and fibula.
Note the wide separation at the tibiofibular joint
indicating rupture of the interosseous membrane.
Small fragments (arrow) are detached from the
lateral process of the talus.
This indicates ligamentous damage.
We have taken illustrative license with the
earlier cases in this section by only providing AP
radiographs. In all instances it is essential to
assess both the AP and lateral radiographs as a
pair. In this patient the AP view shows the
transverse fracture of the lateral malleolus and
the lateral subluxation of the talus. The lateral
view shows the full extent of the fibular fracture
and its displacement. It also allows assessment of
the posterior lip of the tibia, the talus and the
calcaneum.
Base of the 5th metatarsal
An avulsion fracture. This common injury results from
avulsion of the metatarsal tuberosity at the insertion of the
peroneus brevis tendon. The fracture occurs as a
consequence of forced inversion.
Fracture of the base of the 5th
metatarsal.
A twisted ankle (ie if a forced inversion injury)
will often result in a transverse fracture of the
base of the 5th metatarsal. The radiograph shows
a typical appearance.
The calcaneum
The calcaneum is the most commonly injured bone of the
hindfoot. Types of calcaneal fracture are shown on pp. 278–
279. See also infrequent calcaneal injuries on p. 288.
Most severe injuries occur following a fall from a
height.
The fracture partly results from the talus
driving into the calcaneum, like a wedge of steel
slamming down into a block of wood.
If a calcaneal fracture is suspected then an
axial view should be obtained.
The fractures (arrows) through the body of the
calcaneum are well shown.
Some fractures, particularly those involving the
anterior process of the calcaneum (arrow), can
result from a simple twisting injury.
Several types of calcaneal fracture
Intra-articular (75%)
Intra-articular fractures (arrows) involve the
subtalar joint (left) or calcaneo-cuboid joint
(right).
Some fractures will only become apparent
when Bohler's angle is assessed on the lateral
view (above).
This angle is normally 30–40°. If the fracture
results in flattening of the bone then the angle
will be considerably less than 30° (above right).
Flattening of Bohler's angle is the dominant
feature in the calcaneal fracture shown in the
radiograph on the right.
Extra-articular (25%)
Usually more difficult to detect compared with intraarticular fractures.
Extra-articular fractures involve the posterior
part of the calcaneum or, alternatively, the
anterior process of the bone1,4,8. Most of these
fractures are sustained following a fall on the
heel, but not from a great height. Occasionally a
twisting injury may be the cause.
A sclerotic line or density in the body of the
calcaneum (arrow) may be the only evidence of
an impacted fracture. This is an extra-articular
fracture through the tuberosity of the calcaneum
and was sustained during a relatively minor fall
on to the heel.
Growth plate (Salter–Harris) fractures
▪ Relatively common in children. A distal growth plate
injury of the tibia is second in frequency to an injury of the
distal growth plate of the radius.
▪ Growth plate fractures are described in detail on pp. 14–
17.
▪ The most common growth plate fractures (types 1–4) are
shown below.
The Salter–Harris classification/description of the
fractures that involve the growth plate.
Salter–Harris type 2 fracture of the
tibia.
A type 2 fracture is the most commonly occurring
of the fractures that involve the growth plate.
Ligamentous injuries
Torn medial or lateral ligaments
If there is widening of one side of the mortice joint space
then there is commonly an associated fracture elsewhere.
Suspect widening if the joint space is wider than 4 mm
medially or laterally3. Caution: the radiographs may
appear normal even when there is severe ligamentous
damage. Sometimes stress views will be required.
Fracture of the fibula.
The widened medial joint space indicates an
associated ligamentous tear/rupture (the deltoid
ligament).
Tear of the interosseous membrane
This injury is very easy to overlook1,5,9,10. The AP radiograph
will often provide evidence of a tear/rupture. Look for
widening of the space between the distal tibia and the
fibula. A useful rule of thumb: suspect a tear of the tough
tibiofibular syndesmosis whenever the distal tibia and
fibula do not overlap slightly on the AP mortice view.
Also … apply the 6 mm rule (see p. 270).
The wide separation between the tibia and the
fibula indicates a major tear of the interosseous
membrane (the syndesmosis).
This membrane is a fairly rigid structure. It
holds the shafts of the tibia and fibula together,
and extends downwards from the superior to the
inferior tibiofibular joint.
Infrequent but important injuries
Fractures of the talus
Talar fractures are rare. Many result from a high energy
injury, often a road traffic accident or a fall from a height.
Body of the talus4,11
Fractures (arrows) can occur in the coronal,
sagittal or horizontal planes.
Neck of the talus4,11
An important injury because of the high risk of subsequent
avascular necrosis (AVN) and secondary degenerative
arthritis. AVN is caused by disruption of the blood supply to
the body of the talus. Displacement of the fracture
increases the probability of AVN. A displaced fracture is
easy to detect. An undisplaced fracture is easy to overlook.
Displaced fracture through the neck of the talus
(arrow).
Undisplaced fracture through the neck of the
talus (arrow).
Talar dome–osteochondral fracture
A small but clinically important impaction fracture, usually
consequent on an inversion injury1,12. The term
osteochondritis dissecans was used in early descriptions of
this lesion when it was assumed that the pathology was a
spontaneous necrosis of bone in the dome of the talus. It is
now generally accepted that most of these lesions are
actually osteochondral fractures resulting from trauma.
In many cases the talar lesion is not an acute injury but
has resulted from an earlier shearing or compression force.
An osteochondral fracture is identified as either
a focal defect (ie a lucent area) or an irregularity
of the cortex. Most frequently situated on the
medial or lateral aspect of the talar dome.
Sometimes a small fragment will be detached
from the dome and lie free within the joint.
Maisonneuve fracture
The ankle joint is in effect a bone ring and this particular
ring extends as high as the knee because of the strong
tibiofibular interosseous membrane. On occasion an
external rotation injury of the ankle may cause an ankle
injury but in addition the forces/energy acting within the
interosseous membrane (the tibiofibular syndesmosis) may
extend to the upper leg and cause a fracture of the
proximal fibula13. The high fibular fracture may be
overlooked because the main symptoms are around the
ankle joint.
This combination injury is known as a Maisonneuve
fracture. Suspect this injury whenever clinical examination
of the upper leg is painful.
Maisonneuve fracture. Subluxation of the
talus and evidence of rupture of the interosseous
membrane.
The upper leg was painful and an additional
radiograph revealed the high fracture of the shaft
of the fibula.
Distal tibial fractures involving the
articular surface
These fractures are rare, accounting for less than 1% of
fractures of the lower limb14.
The usual cause: a high energy fall or RTA producing a
compression
fracture,
often
with
comminution.
Compression fractures of the tibia are rare because it is
usually the calcaneum that received and accepts the major
vertical force and is fractured.
Both patients had fallen from a height.
Comminuted
fracture
of
the
tibia
with
involvement of the articular surface (arrows).
Complex Salter–Harris fractures
These two fractures are rare but need to be recognised
early, as accurate reduction is essential in order to ensure
normal growth and to avoid subsequent ankle deformity.
Triplane fracture3,15,16
This Salter–Harris type 4 fracture is a complex multidirectional fracture of the tibial epiphysis. It is a three
plane fracture. As follows:
▪ Sagittal plane: vertical fracture through the epiphysis.
▪ Horizontal plane: transverse fracture through the growth
plate.
▪ Coronal plane: vertical fracture through the metaphysis.
Always suspect this complex fracture whenever the AP
view shows a vertical fracture through the tibial epiphysis.
Suspicion necessitates CT for full evaluation.
Pitfall: the full extent of the injury is often not evident on
plain radiography.
Triplane fracture.
The fracture lines are indicated by the arrows.
The subsequent CT (right) shows the fracture in
exquisite detail.
Tillaux fracture3,16
This Salter–Harris type 3 fracture is an avulsion fracture
through the tibial epiphysis. The fracture involves a
partially closed epiphysis (age 11–15 years). It occurs in
adolescents in whom the medial part of the growth plate
has fused, but the normal fusion has not yet reached the
lateral aspect. It is a two plane fracture. As follows:
▪ Vertical plane: through the epiphysis.
▪ Horizontal plane: through the lateral part of the growth
plate.
Pitfall. This fracture can sometimes be confused with a
Triplane fracture on plain radiography. CT will distinguish.
Tillaux fracture.
This Salter–Harris type 3 fracture limited to the
lateral aspect of the epiphysis and growth plate is
well shown on the lateral and AP radiographs
(arrows).
Infrequent calcaneal fractures
Avulsion fracture of the calcaneal tuberosity
(arrows). It represents an avulsion of the Achilles
tendon with part of the calcaneum. Occurs most
commonly in an elderly patient with severe
osteoporosis.
Fatigue fractures due to repetitive stress are
rare but do occur. Usually identified as an area of
bone sclerosis on the lateral radiograph (arrow).
Os trigonum fracture17
The os trigonum is an elongation/enlargement
of the posterior process of the talus. It is present
in approximately 50% of feet and can be fused to
the posterior aspect of the talus or it can be a
free bone on its own. A fracture of a fused os
trigonum can occur during a twisting injury at the
ankle joint. A very high index of clinical suspicion
is essential in order to raise the suggestion of a
fracture. The two examples shown here are
normal.
Talar dislocations—Infrequent but
important
The subtalar joint has two parts and either part can
dislocate as a result of a high energy force.
Dislocation of the talocalcaneal joint.
The talonavicular and talocalcaneal articulations
are not anatomical—compare this with the
normal articulations on the opposite page.
Several fractures/fracture fragments are also
present.
Dislocation of the talonavicular joint.
Note that the head of the talus overlaps, ie it is
displaced anterior to, the articular surface of the
navicular bone (arrowheads).
The normal appearance at the talonavicular
joint is shown in the other figures on the page
opposite.
Pitfalls
Calcaneum: the apophysis
The normal calcaneal apophysis can appear
very irregular, fragmented and/or sclerotic, as in
these two examples.
Calcaneum: the anterior process
A fracture of the anterior process (p. 279) is a
common injury. However, the anterior process
can develop from a secondary ossification centre.
If this centre does not unite with the parent bone
it (the os secundum) can be mistaken for a
fracture. Distinguishing between a fracture and
an os secundum will depend on correlation with
the clinical findings.
Normal accessory ossicles
Small bones lying adjacent to the tips of the medial and
lateral malleoli are very common. They may be misread as
avulsed fracture fragments. Occasionally an ossicle will be
difficult to distinguish from a fracture and clinical
correlation is important. Fractures are tender, accessory
ossicles are not. Also:
▪ An accessory ossicle has a well defined (ie corticated)
outline.
▪ An acute fracture fragment is ill defined (ie not
corticated) on one of its sides.
Normal accessory ossicles at tips of the medial
and lateral malleoli in a 10 year old.
A frequent finding.
The os trigonum (arrows). A common normal
variant (p. 288). It may be attached to, or
separate from the talus.
References
1. Brandser EA, Braksiek RJ, El-Khoury GY, et al.
Missed fractures on emergency room ankle
radiographs: an analysis of 433 patients. Emergency
Radiology. 1997;4:295–302.
2. Brandser EA, Berbaum KS, Dorfman DD, et al.
Contribution of Individual Projections Alone and in
Combination for Radiographic Detection of Ankle
Fractures. Am J Roentgenol. 2000;174:1691–1697.
3. Daffner RH. Ankle Trauma. Semin Roentgenol.
1994;29:134–151.
4. Prokuski LJ, Saltzman CL. Challenging fractures of
the foot and ankle. Rad Clin North Am.
1997;35:655–670.
5. Harper MC, Keller TS. A radiographic evaluation of
the tibiofibular syndesmosis. Foot Ankle.
1989;10:156–160.
6. Hamblen DL, Simpson HR. Adams's Outline of
Fractures including joint injuries. 12th edn.
Churchill Livingstone; 2007.
7. Porter S. Tidy's Physiotherapy. 15th edn. Churchill
Livingstone: Elsevier; 2013.
8. Slatis P, Kiviluoto O, Santavirta S, Laasonen EM.
Fractures of the calcaneum. J Trauma. 1979;19:939–
943.
9. Ramsey PL, Hamilton W. Changes in tibiotalar area
of contact caused by lateral talar shift. J Bone Joint
Surg Am. 1976;58:356–357.
10. Edwards GS, Delee JC. Ankle diastasis without
fracture. Foot Ankle. 1984;4:305–312.
11. Rammelt S, Zwipp H. Talar neck and body fractures.
Injury. 2009;40:120–135.
12. Canale ST, Belding RH. Osteochondral lesions of the
talus. J Bone Joint Surg Am. 1980;62:97–102.
13. Anderson S. Lower extremity injuries in youth
sports. Pediatr Clin North Am. 2002;49:627–641.
14. Calori GM, Tagliabue L, Mazza E, et al. Tibial pilon
fractures: which method of treatment? Injury.
2010;41:1183–1190.
15. Chan O. ABC of Emergency Radiology. 3rd edn.
Wiley Blackwell; 2013.
16. Weinberg AM, Jablonski M, Castellani C, et al.
Transitional fractures of the distal tibia. Injury.
2005;36:1371–1378.
17. Anwar R, Nicholl JE. Non union of a fractured os
trigonum. Injury Extra. 2005;36:267–270.
17
Midfoot & forefoot
Normal anatomy
AP view 294
Oblique view 294
Cuneiform mortice and the Lisfranc joints 295
Analysis: the checklists
The AP radiograph 296
The oblique radiograph 296
The lateral radiograph 297
The common fractures
Metatarsals and phalanges; base of the 5th
metatarsal 298
Fatigue (march/stress fractures) 299
Infrequent but important fractures
Tarsal bone fractures 300
Base of the 2nd, 3rd or 4th metatarsal 300
Jones fracture 301
Dislocations/subluxations
The tarsometatarsal joints: Lisfranc injuries 302
Pitfalls
Sesamoids and accessory ossicles; apophysis;
epiphyseal clefts; an unrelated abnormality can
cause distraction; an error/pitfall that needs
repeated emphasis 304
Regularly overlooked injuries
▪ Lisfranc subluxations.
▪ Fatigue fractures involving the 2nd or 3rd
metatarsals.
▪ Avulsion fracture of the base of the 5th
metatarsal—overlooked on ankle radiographs.
The standard radiographs
Protocols vary. In the UK a two view series is
commonplace: AP and Oblique. Elsewhere, and
in the USA, a three view series is common
practice1,2: AP, Oblique, and a Lateral.
Abbreviations
AP, anterior-posterior; MT, metatarsal.
Normal anatomy
The bones of the midfoot form an arch. As a consequence
several of the tarsal bones, specifically the three cuneiform
bones and the bases of the metatarsals, overlap on both the
AP and oblique projections. The individual bones can be
separated from one another when the AP and oblique
radiographs are examined as a complementary pair.
AP view
Oblique view
The cuneiform mortice and the
Lisfranc joints
The base of the 2nd metatarsal is held in a mortice created
by the three cuneiform bones. This mortice helps to
prevent lateral slip of the bases of the metatarsals during
weight bearing.
Alignment of 2nd metatarsal and the intermediate
cuneiform. May appear “notched”.
Alignment of 3rd metatarsal and the lateral cuneiform.
May appear “notched”.
Analysis: the checklists
Analysis of the images will be influenced by the clinical
findings such as the precise site of swelling, bruising,
tenderness and pain.
The AP radiograph
Check:
1. Metatarsal and phalangeal shafts.
2. The Lisfranc joints. Always ask yourself … does the
medial margin of the base of the 2nd metatarsal align
with the medial margin of the cuneiform bone?
AP view.
Metatarsal shafts—normal. 2nd metatarsal aligns
correctly with the intermediate cuneiform bone.
The oblique radiograph
Check:
1. Metatarsal shafts.
2. The Lisfranc joints. Does the medial margin of the base
of the 3rd metatarsal align with the adjacent cuneiform
bone?
3. The hindfoot bones and the hindfoot–midfoot
articulations.
Oblique view.
Metatarsal shafts—normal. 3rd metatarsal aligns
correctly with the lateral cuneiform bone.
The lateral radiograph
Check:
1. Base of the 5th metatarsal.
2. The hindfoot bones and the midfoot articulations.
Lateral view.
Base of 5th metatarsal—fracture (arrow).
Midfoot articulations—normal.
The common fractures
Metatarsals and phalanges
▪ Very common. Some 35% of all foot fractures are
metatarsal injuries3. In general, detection of a fracture
involving any of the medial four metatarsals is easy.
▪ As many as 70% of all metatarsal fractures involve the
5th metatarsal2.
Base of the 5th metatarsal
A fracture of the tuberosity represents an avulsion injury
resulting from contraction of the peroneus brevis muscle
and the pull of the plantar aponeurosis. It is caused by a
plantar flexion–inversion injury.
A patient presenting with a twisted ankle: careful clinical
examination of the base of this metatarsal will indicate
when radiography of the foot, not the ankle, is necessary.
Potential pitfall: The normal unfused apophysis
at the base of the 5th metatarsal is present in all
children. It should not be misinterpreted as a
fracture.
Helpful rules:
An avulsion fracture is situated either
transverse or oblique to the long axis of the 5th
metatarsal.
The normal childhood apophysis lies away from
the articular surface and its long axis is aligned in
a direction which is almost parallel with that of
the shaft of the metatarsal.
Injured base of 5th MT.
The horizontal line crossing the metaphysis is a
fracture. The separate pieces of bone represent a
normally developing apophysis.
Fatigue (march/stress) fractures
These injuries are frequently missed, misdiagnosed,
mistreated, and misunderstood4.
The 2nd and 3rd metatarsals are most commonly
affected.
Radiographs are only abnormal when the fracture is well
established. Abnormalities may not be visible for two or
more weeks after the onset of symptoms.
If clinical suspicion of a fatigue fracture is high and the
initial radiographs appear normal, it is worth considering a
radionuclide bone study. Localised increase in uptake of the
radiopharmaceutical in the context of a relevant history is
diagnostic of a fatigue fracture. Alternatively, in (say) an
elite athlete or footballer a similar suspicion would justify
an MRI which would quickly confirm or exclude a fatigue
fracture.
Fatigue fractures.
Four radiographic patterns may be present: (a)
Normal; (b) Transverse or oblique crack (3rd
metatarsal); (c) Faint periosteal reaction or fluffy
callus (3rd metatarsal); and (d) Profuse callus
(3rd metatarsal).
Infrequent but important fractures
Tarsal bone fractures
Midfoot tarsal bone fractures are uncommon, frequently
resulting from high energy trauma. A major injury will be
clinically obvious.
A fragment is detached from the lateral aspect
of the cuboid (arrow). All the other bones and
joints are normal.
Not a fracture. This is a very common normal
finding (arrow). It is an accessory ossicle (os
naviculare).
Base of the second, 3rd, or 4th
metatarsal
Any fracture, whether a major fracture or a very small
flake, at any of these sites will signal that there might be a
major injury to a tarsometatarsal joint (a Lisfranc joint).
See pp. 302–303.
A fragment (arrow) has been detached from the
base of the 2nd metatarsal. The base of this
metatatarsal has subluxed laterally.
A large fragment (arrow) is detached from the
base of the 3rd metatarsal. The shaft of the 3rd
metatarsal (ie the distal fragment) has subluxed
laterally.
Jones fracture1,2,4–6
Two different fractures involve the proximal shaft of the 5th
metatarsal: the very common avulsion injury (p. 298), and
the much rarer but clinically important Jones fracture. It is
important not to confuse these two fractures.
Jones fractures do not result from a simple avulsion
injury.
The Jones fracture was first described by an orthopaedic
surgeon, Robert Jones. He sustained the injury and
subsequently published his experience7. Descriptions of
this fracture in the literature are often confusing.
Clarification: a Jones fracture is a transverse fracture
that lies distal to the styloid process of the fifth metatarsal,
ie distal to the articulation between the bases of the 4th
and 5th metatarsals. Characteristically it is positioned
within 1.5 cm of the tuberosity.
A Jones fracture occurs as an acute injury, or,
alternatively, following repeated stress affecting this
metatarsal. Consequently some Jones fractures are fatigue
fractures.
▪ The acute version results from a vertical or mediolateral
force acting on the base of the metatarsal.
▪ The fatigue fracture version results from chronic
overloading on the metatarsal, commonly in young
athletes.
Delayed union or non-union are common problems,
especially with a Jones fatigue fracture. In an elite athlete
fixation with an intramedullary screw is often required.
(a) Typical avulsion fracture of the tuberosity.
Prognosis is excellent.
(b) Jones fracture (arrow). Non-union is a
relatively common complication.
Dislocations/subluxations
Direct trauma commonly results in metatarsophalangeal or
interphalangeal joint dislocations. These do not cause any
difficulty in terms of diagnosis.
Injury to the tarsometatarsal joints5,8–
11
Infrequent but very important. Walking and weight-bearing
depend on the accurate alignment of the tarsometatarsal
joints (see p. 295). Even a very slight subluxation requires
meticulous reduction/management in order to preserve or
restore function.
▪ Traumatic subluxations at the bases of the metatarsals (ie
Lisfranc injuries) will be overlooked unless the normal
alignment of the bones is carefully assessed. The
radiographic appearance is often subtle. Always ask two
questions:
1. On the AP view does the medial margin of the base
of the 2nd metatarsal align with the medial margin
of the intermediate cuneiform?
2. On the oblique view does the medial margin of the
3rd metatarsal align with the medial margin of the
lateral cuneiform?
▪ Subluxation at a Lisfranc joint can occur with or without
a fracture.
▪ Suspect a tarsometatarsal subluxation whenever a
fragment of bone—however small—is detached from the
base of any of the medial four metatarsals.
Lisfranc subluxation: fracture near the base of
the 2nd metatarsal has freed the shaft of this
bone from the restraining cuneiform mortice.
Lateral slippage of the metatarsal bases has
occurred in this patient.
Lisfranc subluxation: the ligaments holding the
3rd metatarsal to the lateral cuneiform bone have
been ruptured. Consequently, the 3rd metatarsal
has subluxed laterally. The answer to question (2)
at the botton of p. 296 is “No”.
The reasons why some Lisfranc subluxations are
overlooked on the radiographs8–10:
▪ Medical: failure to inspect the radiographs carefully.
▪ Medical: ignoring the importance of a tiny flake of bone
avulsed from the base of the 2nd or 3rd metatarsal. A tiny
flake is a big warning.
▪ Technical: the subluxation may have temporarily reduced
because the radiograph is taken with the patient supine
and not weight bearing. Apply this rule: whenever there is
clinical concern regarding a possible Lisfranc injury and
the radiographs appear normal then repeat the
radiographs whilst weight bearing. Alternatively, CT or
MRI imaging will be diagnostic11.
Terminology8,9:
J. Lisfranc was a surgeon in Napoleon's army. He
devised a forefoot amputation that took less than
one minute to perform on soldiers who had
frostbite or other injury. The amputation was
through
the
tarsometatarsal
joints.
His
imagination and skill has been rewarded by this
series of eponyms.
▪ Lisfranc joint or joints: the tarsometatarsal
joints
▪ Lisfranc joint complex: a description used by
some when referring to the tarsometatarsal
articulations.
▪ Lisfranc injury: a low-impact midfoot sprain. It
is relatively common in athletes including
American football players.
▪ Lisfranc subluxation: a high energy injury
resulting in subluxation at a Lisfranc joint.
Pitfalls
Sesamoids and accessory ossicles
Numerous small bones are present on foot radiographs,
and can be erroneously read as fracture fragments.
The most common sesamoid bones and the os
naviculare.
The os naviculare (arrow). Also known as the os
tibiale externum.
Three sesamoid bones and the os trigonum.
These are the normal bones that cause concern or
are questioned most frequently.
Another common accessory ossicle is the os
trigonum. It lies posterior to the talus. Sometimes
the ossicle is fused to the talus.
Apophysis
Normal apophysis at the base of the 5th
metatarsal read as avulsion fracture (p. 298).
Normal apophyses. 100% of children have this
apophysis. It usually ossifies as a single entity, but
it may show multicentric ossification as in these
three examples.
Epiphyseal clefts12,13
Defects or clefts occur normally in some epiphyses. They
close around puberty. The basal epiphysis of the proximal
phalanx of the great toe is a relatively common site. These
clefts must not be confused with fracture lines.
A cleft epiphysis.
A normal anatomical variant. This is the most
common site of a cleft epiphysis.
An unrelated abnormality can cause
distraction
Careful history taking and clinical examination is crucial to
the correct assessment of the radiographs. Sometimes an
unrelated abnormality will distract the unwary.
Injured midfoot.
The irregular and fragmented head of the 2nd
metatarsal is not a recent injury. In this particular
patient it could distract the unwary. It is a
Freiberg's infraction. The important injury is at
the base of the 2nd metatarsal where there is
subluxation (arrow) at the Lisfranc joint.
Freiberg's
infraction:
flattening
and
fragmentation of the head of the metatarsal.
Often associated with swelling, tenderness and
pain. Most commonly seen in young women. Its
aetiology remains obscure.
An error/pitfall8–10 that needs
repeated emphasis …
A foot is injured and an injury to a Lisfranc joint is a clinical
possibility but the joint appears normal on the radiographs.
An injury to the ligaments could still be present if
spontaneous reduction of a subluxation has occurred.
Remember that the radiographs are obtained as non
weight-bearing images and the joint is not under the stress
that occurs when the patient is standing. Weight-bearing
views (or CT or MRI) should be obtained when there is
continuing clinical concern in relation to a Lisfranc joint.
References
1. Berquist TH. Imaging of the foot and ankle. 3rd ed.
Lippincott Williams and Wilkins; 2010.
2. Zwitser EW, Breederveld RS. Fractures of the fifth
metatarsal; diagnosis and treatment. Injury.
2010;41:555–562.
3. Spector FC, Karlin JM, Scurran BL, Silvani SL.
Lesser metatarsal fractures. Incidence, management
and review. J Am Podiatry Assoc. 1984;74:259–264.
4. Anderson EG. Fatigue fractures of the foot. Injury.
1990;21:275–279.
5. Prokuski LJ, Saltzman CL. Challenging fractures of
the foot and ankle. Radiol Clin North Am.
1997;35:655–670.
6. Shereff MJ, Yang QM, Kummer FJ, et al. Vascular
anatomy of the fifth metatarsal. Foot Ankle.
1991;11:350–353.
7. Jones R. Fracture of the base of the fifth metatarsal
bone by indirect violence. Ann Surg. 1902;35:697–
700.
8. Hatem SF. Imaging of Lisfranc injury and midfoot
sprain. Radiol Clin North Am. 2008;46:1045–1060.
9. Punwar S, Madhav R. Subtle Lisfranc complex
injury: when not to trust normal Xrays. Injury Extra.
2007;38:250–254.
10. Sherief TI, Mucci B, Greiss M. Lisfranc injury: How
frequently does it get missed? And how can we
improve? Injury. 2007;38:856–860.
11. Kalia V, Fishman EK, Carrino JA, Fayad LM.
Epidemiology, imaging, and treatment of Lisfranc
fracture-dislocations revistied. Skel Radiol.
2012;41:129–136.
12. Keats TE, Anderson MW. Atlas of normal Roentgen
variants that may simulate disease. 9th ed. Elsevier;
2012.
13. Harrison RB, Keats TE. Epiphyseal clefts. Skel
Radiol. 1980;5:23–27.
18
Chest
Normal anatomy
Frontal CXR—the lungs, lung markings, hila,
cardiothoracic ratio 308
Lateral CXR—the lobes of the lung, skeletal shadows,
normal features 310
Analysis: the checklists
The frontal CXR 312
The lateral CXR 314
Ten clinical problems
Is there pneumonia (consolidation)? 316
Is there a pneumothorax? 319
Are there signs of left ventricular failure? 321
Severe asthmatic attack—is there a complication?
323
Is there a pleural effusion? 324
Is there an aortic dissection or traumatic rupture of
the aorta? 326
Is there a rib fracture? 327
Is there a cause for non-specific chest pain? 327
Is there evidence of a pulmonary embolus? 327
Is there evidence of an inhaled foreign body? 328
The chest X-ray (CXR)
A comprehensive description of the information
that can be provided by the CXR requires a
textbook all of its own.
Our companion book The Chest X-Ray : A
Survival Guide1 will assist you to get the very
best from this, the commonest radiological
investigation in an Emergency Department (ED).
In this chapter we focus on the ten most
common clinical questions that are asked of a
CXR in the ED.
The standard radiographs
PA CXR. A lateral CXR in selected cases.
Abbreviations
CTR, cardiothoracic ratio;
CXR, chest X-ray;
LLL, left lower lobe;
LUL, left upper lobe;
LVF, left ventricular failure;
ML, middle lobe;
PA, posterior-anterior;
RLL, right lower lobe;
RUL, right upper lobe;
T3, the 3rd thoracic vertebra.
Normal anatomy
Frontal CXR—the lungs
The tricky hidden areas.
The four areas where small (and large) lung
lesions are overlooked.
Frontal CXR—lung markings
Normal lung markings are solely due to vessels and to
nothing else. The normal bronchial walls, normal
interstitium, and normal lymphatics are not visible.
There is a complete absence of any lung
markings in the lung immediately adjacent to
each costophrenic angle.
In this peripheral part of the lung the normal
vessels are simply too small to be visualised.
If this area shows detectable markings, then
interstitial disease, or oedema, is likely1.
Frontal CXR—hila
The hilum is the site at which the bronchi and vessels enter
or leave the lung.
The two hila are approximately the same size
and of very similar density.
The hilar shadows are due to pulmonary
arteries and pulmonary veins. X marks the main
pulmonary trunk.
Blue = pulmonary trunk and pulmonary arteries;
Red = pulmonary veins;
Lilac = part of left atrium.
Frontal CXR—cardiothoracic ratio
Most normal hearts have a cardiothoracic ratio (CTR) of
less than 50% when assessed on a PA chest radiograph
obtained in full inspiration2.
Measuring the CTR.
Two lines are drawn tangential to the outermost
aspects of the right and left sides of the heart and
the maximum cardiac width is measured.
The transverse diameter of the thorax is
measured as the maximum internal width of the
thoracic cage (ie inner cortex of rib to inner
cortex of rib).
a/b < 50%.
Cardiac silhouette. The left and right borders of
the heart are well defined by the surrounding air
in the lungs.
Lateral CXR—the lobes of the lung
The two fissures in the right lung divide the lung into three
lobes.
The single fissure in the left lung divides the lung into
two lobes.
The oblique fissure on each side is propeller shaped and
consequently we only, and very occasionally, see a part of a
fissure on a normal lateral CXR.
On the other hand, we will see most of the horizontal
fissure on the lateral CXR because it is straight. We will
often see this fissure on the frontal CXR for the same
reason.
Lateral CXR—skeletal shadows
The scapula shadows (blue) are usually evident
… but rarely create any difficulties.
The oblique shadows of the ribs are always
evident.
The vertebrae are always seen.
Lateral CXR—three normal
appearances
A normal lateral CXR will show three normal
features relating to the two lungs (which project
one over the other):
(1) The vertebral bodies gradually appear
blacker as you look from T3 down to T12
…“grey at top; black at bottom”.
(2) Both domes of the diaphragm are clearly
visualised. Note that the anterior aspect of
one dome (the left dome) fades away because
the heart is positioned on this part of the
dome.
(3) There is no abrupt change in density over
the cardiac shadow. (Of course, any overlying
rib shadows need to be discounted).
Analysis: the checklists
The frontal CXR
Four steps underpin accurate analysis.
1. Check whether the CXR is a PA or an AP radiograph and
whether it was obtained erect or supine. An AP CXR will
magnify the heart shadow; a supine CXR will alter the
position of pleural air or pleural fluid.
2. Check whether there is an adequate inspiration. A small
inspiration alters the normal appearance of the heart and
lung bases.
3. Direct your initial analysis to your primary clinical
concern. Is your primary concern: a left sided
pneumothorax? A right sided pleural effusion? A coin
lodged in the oesophagus?
4. Now you can assess the radiograph in an organised and
systematic manner. As follows:
□ Is the heart enlarged?
In an adult, the cardiothoracic ratio (CTR) should be <
50% on a PA CXR (see p. 309).
□ Are both domes of the diaphragm clearly seen and
well defined?
If part of a dome is obscured, suspect pathology in the
adjacent lower lobe.
□ Are both heart borders clearly seen and well defined?
If not, there is a high probability of pathology in the
immediately adjacent lung.
□ Are the hila normal … position, size, density?
□ Check the tricky hidden areas of the lung: both
apices, behind the heart shadow, around each hilum,
below the diaphragm (see p. 308).
□ Are the bones normal?
□ Finally, ask yourself once again:
Have I addressed this patient's particular clinical problem?
Normal PA CXR.
▪
▪
▪
▪
▪
Good inspiration.
Heart size normal.
Both domes of the diaphragm well defined.
Both heart borders well defined.
Hila unremarkable.
Is there an adequate inspiration? PA CXRs
of the same patient: (a) is a good inspiration; (b)
is a very poor inspiration. In (b) the heart appears
enlarged and the lung bases hazy with crowding
of vessels. These appearances are bogus; they are
due to the extremely poor inspiration. CXR (a) is
normal.
Are both domes of the diaphragm
clearly seen and well defined?
Both domes of the diaphragm will be well defined
if the adjacent lung is normal. In this patient,
presenting with chest pain and fever, much of the
left dome is obscured. This is due to pus in the
adjacent alveoli.
Diagnosis: left lower lobe pneumonia.
Are both heart borders clearly seen and
well defined?
Both heart borders will be well defined if the
adjacent lung is normal. In this patient with a
cough and fever the right heart border is
obscured because the air in the adjacent lung has
been replaced by pus.
Diagnosis: middle lobe pneumonia.
The lateral CXR
Four questions underpin accurate analysis:
1. Are the vertebral bodies becoming blacker from above
downwards?
If not (ie they are becoming whiter or greyer) then
suspect disease in a lower lobe or in a pleural space.
2. Are the domes of the diaphragm clearly visualised?
Remember that one dome, the left dome, disappears
anteriorly because the heart is tight up against it. If any
other part of either dome is obscured—suspect
consolidation or collapse in the adjacent lung.
3. Is there any abrupt change in density across the heart
shadow?
“An abrupt change in density” is likely to be a lung
abnormality.
4. Have I correlated my findings on the lateral CXR with
the frontal CXR appearances?
Normal lateral CXR.
▪ Vertebral bodies are “blacker” at the T9–T12
levels. Remember the rule: “grey at top; black at
bottom”.
▪ Both domes of the diaphragm are sharply
defined.
▪ No abrupt change in density over the cardiac
shadow.
Female patient with cough and fever of recent
onset. The lateral CXR is abnormal: (1) The
vertebral bodies appear whiter at the T9–T12
level; (2) only one dome of the diaphragm is
sharply
defined.
Conclusion:
lower
lobe
pneumonia. The frontal CXR confirms that the
pneumonia is situated behind the heart in the left
lower lobe.
Patient with a fever and right sided chest pain.
The lateral CXR is abnormal. The main finding is
that there is an “abrupt change in density over
the cardiac shadow”. This density is white,
extends inferiorly from the hilum, and has sharp
margins superiorly and inferiorly. The density
represents collapse within the middle lobe of the
right lung. This is shown in the explanatory
drawing. (The dotted line indicates the position of
the oblique fissure in the right lung.)
Ten clinical problems
The full breadth of the radiology of thoracic disease as
revealed by the plain CXR is addressed in our companion
book The CXR: A Survival Guide1. We cannot cover that
detail in this single chapter.
Instead, we will consider the ten clinical problems that
account for well over 90% of all CXR requests made in the
Emergency Department. We will take each problem in turn
and pose a clinical question of the frontal CXR.
Question 1: Is there pneumonia
(consolidation)?
Physical examination is not always sufficiently accurate on
its own to confirm or exclude the diagnosis of pneumonia3.
Many pneumonias will be obvious on the frontal CXR. Some
are much more difficult to detect—the hidden pneumonias.
Detecting a hidden pneumonia
▪ Search for any evidence of a silhouette sign1,2,4 on the
CXR.
▪ Assess the mediastinal and diaphragmatic
boundaries/borders.
▪ When a border is ill-defined, the precise site of a
concealed area of consolidation is revealed. Sometimes
the loss of a border is much more obvious than the actual
air space density that occurs with a pneumonia.
The silhouette sign. An intrathoracic lesion or
density touching a border of the heart, aorta, or
diaphragm will obliterate part of the border on
the CXR1,2.
Explanation: the borders of the heart and both
domes of the diaphragm are visible on a normal
CXR because the air in the lung contrasts with
the water density of the heart and diaphragm. If
lung air is replaced by pus (pneumonia) the
immediately adjacent border will disappear or be
ill-defined. This obliteration is termed the
silhouette sign.
What does the word “consolidation”
mean?
When lung alveoli fill with fluid (pus, water, or
blood) there will be a shadow on the radiograph.
Although the word “consolidation” is often used
synonymously to imply that the shadow is an area
of pneumonia, this is not strictly correct. There
are other causes for air space shadowing (ie
consolidation) and these include: pulmonary
haemorrhage, pulmonary oedema, and fluid
aspiration.
Hidden pneumonia: checking the
borders
Partly ill-defined or
absent
Suspect consolidation and/or
collapse of the …
Right heart border
Middle lobe (a)
Left heart border
Left upper lobe (b)
Left dome of
diaphragm
Left lower lobe (c)
Right dome of
diaphragm
Right lower lobe (d)
Silhouette sign—Pitfall. Mediastinal fat1.
Some middle aged people accumulate a large
collection of fat adjacent to the heart causing the
heart border to be ill defined. The fat is of lower
density than the water density of lung
consolidation and this difference will help you to
avoid this pitfall. The patient on the left has lost
the sharp silhouette of both the right heart
border and of the right dome of the diaphragm.
The patient on the right has lost the silhouette of
part of the right dome of the diaphragm. In both
cases the cause is a large collection of fat.
Silhouette sign—Pitfall. Depressed
sternum.
The right heart border is effaced, and there is
added
density
suggesting
middle
lobe
consolidation. The lateral CXR shows the
depressed sternum which is the cause of the
grossly abnormal appearance on the frontal CXR1.
The lungs are clear.
Question 2: Is there a pneumothorax?
An erect CXR obtained in full expiration is recommended.
The normal lungs are more opaque (or slightly whiter) on
an expiration CXR. Consequently, when a pneumothorax is
present the air (black) in the pleural space contrasts with
the adjacent (whiter) lung. This accentuation of the
difference in contrast, as compared with an inspiration film,
sometimes makes it slightly easier to detect a
pneumothorax.
A pneumothorax shows three features on the
erect CXR:
▪ A clearly defined line (ie the visceral pleura).
This line parallels the chest wall.
▪ The upper part of this line will be curved at the
lung apex.
▪ An absence of lung markings (ie vessels)
between the lung edge and chest wall.
Shallow pneumothorax. The visceral pleural
line is visible.
Pneumothorax. Note the well-defined line that
represents the lung edge (ie the visceral pleura).
Also, there are no vessels lateral to this line.
Supine CXR. In a severely injured patient the
CXR will inevitably be obtained with the patient
supine. On a supine CXR the pleural air will rise
to the highest point in the pleural space—ie to the
anterior aspect of the thorax. Consequently the
lung base and the area around the heart need
careful evaluation4.
Pitfall. An error rate of over 70% in detecting a
pneumothorax by the trauma team when reading
supine CXRs in the acute setting has been
reported5. An upright CXR or, when this is not
possible, either sonography or an early CT will be
necessary when a pneumothorax is not evident
but needs definite exclusion.
Pitfall. A skin crease in an infant or in the aged,
overlying clothing, sheets, or intravenous lines
can mimic a visceral pleural margin. The CXR
should always be repeated after a rearrangement
of the possible artefacts whenever there is any
doubt as to the precise nature of a presumed lung
edge.
Question 3: Are there signs of left
ventricular failure (LVF)?
Look for cardiac enlargement and for lung and pleural
changes.
Cardiac enlargement.
Almost all patients with LVF have an enlarged
heart. The occasional exception is a patient with
an acute myocardial infarction.
Most enlarged hearts have a cardiothoracic
ratio (CTR) over 50% when assessed on a PA CXR
(p. 309).
The CTR is well over 50% in this patient.
Caveats:
▪ A CTR should not be read as abnormal:
□ on an AP CXR—because of magnification.
□ if the sternum is depressed, or if there is an
exceptionally narrow AP diameter of the
thorax.
□ in some elderly patients when the internal
thoracic diameter is reduced because of bone
(rib) softening.
▪ A heart may be enlarged despite a normal CTR.
If the transverse cardiac diameter was very,
very, narrow when the heart was normal, the
enlargement that has occurred since then may
not have reached 50% of the transverse
diameter of the thorax.
▪ A few normal people (approximately 2%) have a
CTR over 50%2.
LVF; heart, lung and pleural changes.
Erect PA, CXR
Early LVF. Septal lines (Kerley B lines) caused by
fluid in the interstitium. These short, straight
lines reach the pleural surface and have this
characteristic appearance at the lung base.
Early LVF. Small pleural effusions. Slight
blunting of the costophrenic angles. Effusions in
LVF are usually bilateral.
Interstitial oedema. The fluid lies mainly in
the interstitium of the lung (ie oedema within the
alveoli is less evident). Consequently, the
shadowing is predominantly nodular and linear.
Extensive alveolar oedema. The fluid lies
mainly within the alveolar air spaces (ie oedema
lying in the interstitium is much less evident).
Consequently the shadowing has a fluffy or cotton
wool-like appearance.
Question 4: Severe asthmatic attack
—is there a complication?
The complications to look for are lung consolidation, lobar
collapse, pneumothorax and pneumomediastinum.
Lobar collapse. Collapse of the right upper
lobe.
Pneumothorax. Air can dissect through the
lung and in the region of the hilum it may enter
the pleural space. The arrow indicates the
visceral pleural line.
Pneumomediastinum. Streaks of air in the
mediastinal soft tissues.The streaks may extend
up into the neck. In this patient the air has
dissected into the soft tissues around the left
cardiac margin.
Pneumomediastinum explained. Air has
dissected through the lung to the hilum and up
into the neck. It can appear in the soft tissues of
the chest wall. In addition, the dissecting air may
outline a margin of the heart.
Question 5: Is there a pleural
effusion?
Fluid in the pleural space can adopt several different
appearances.
On the erect frontal CXR1
The commonest appearance is a meniscus at a
costophrenic angle. It requires 200–300 ml of
pleural fluid to efface the normal sharp sulcus
between the diaphragm and the ribs. If the
effusion is large, the entire hemithorax is opaque
and the heart is pushed towards the normal side.
Other patterns also occur:
Top: Puddling in a subpulmonary position is
relatively common. A subpulmonary effusion
is usually easier to detect on the left side, where
the puddle in the pleural space can cause the
gastric air bubble to appear widely separate
from the (apparent) superior margin of the
diaphragm.
Bottom left: A linear (lamellar) effusion.
Bottom right: Fluid loculated in the pleural
space. In this example—within the horizontal
fissure.
Small effusion on the patient's right
side (a meniscus is evident).
A larger effusion is present on the left side …
again, a meniscus appearance is evident. Note
that the lung shadows are consistent with
alveolar and interstitial oedema.
Encysted pleural fluid.
(1) In the horizontal fissure.
(2) Posteriorly in the pleural space. The latter
has produced a “blob like” appearance
(without a sharp superior margin) overlying
the lower zone of the right lung.
On the supine CXR1
Pleural fluid on a supine CXR1.
The fluid spreads to the most dependent site (ie
to the posterior aspect of the pleural space). This
causes
the
right
hemithorax
to
appear
greyer/whiter than the opposite side.
In this patient almost all of the shadowing over
the right hemithorax is due to a large pleural
effusion.
Question 6:
(a) Is there an aortic dissection?
(b) Is there a traumatic rupture of the aorta?
When assessing the mediastinum there are no absolute
measurements that indicate abnormal widening on a
frontal CXR.
Aortic dissection4,6,7
▪ The CXR is often normal.
▪ In the appropriate clinical setting mediastinal widening,
with or without a left pleural effusion, is highly suggestive.
▪ Always compare the present CXR with any previous CXR,
if available. An alteration to the mediastinum may be
obvious.
▪ Clinical suspicion of a dissection must take priority over a
normal CXR, and additional imaging becomes mandatory
in all cases.
Traumatic rupture8–10
▪ 30% of patients with an aortic rupture have a normal CXR
on presentation. If the CXR is normal, the level of clinical
concern will determine whether an additional definitive
radiographic examination (for example CT) is needed.
▪ A widened mediastinum does not necessarily indicate
aortic rupture following blunt trauma to the chest. Tearing
of small mediastinal veins is the most common cause of
mediastinal widening on the CXR.
Pitfall.
In middle-aged and elderly patients, the aorta will
often show age-related unfolding. Furthermore,
on an AP projection an unfolded but otherwise
normal aorta can be considerably magnified.
This patient has an unfolded aorta.
Question 7: Is there a rib fracture?
Oblique views of the ribs are not indicated following a
relatively minor injury to the thorax. Clinical management
is rarely altered by demonstration of a simple rib fracture.
A frontal CXR is obtained solely to exclude an important
complication such as a pneumothorax.
Pitfalls.
When recording a diagnosis of “no rib fracture”,
remember:
1. A fracture through a costal cartilage will not
be visible on a CXR. Cartilage, unlike bone, is
radiolucent.
2. A fracture through the bone may be present
but it will not be detectable unless there is
some displacement. Many rib fractures are
initially undisplaced.
Question 8: Is there a cause for nonspecific chest pain?
In many of these patients the pain remains unexplained and
the CXR is normal.
Systematic analysis of the CXR (p. 312) will sometimes
reveal an unexpected cause of the pain (eg pneumothorax,
spontaneous pneumomediastinum11, rib fracture).
The main pitfalls.
Over reading or under reading a CXR
appearance.
▪ Example of over reading: an unfolded aorta
read as an aortic dissection.
▪ Example of under reading: casual inspection
overlooks an apical pneumothorax.
Question 9: Is there evidence of a
pulmonary embolus?1,4
90% of emboli occur without pulmonary infarction and the
CXR often appears normal.
Sometimes non-specific CXR findings are present,
including: small areas of linear collapse; a small pleural
effusion; slight elevation of a dome of the diaphragm.
Whenever a pulmonary embolus remains a clinical
possibility then—whatever the CXR findings—the patient
requires definitive imaging, usually a CT pulmonary
angiogram.
Pitfall.
Unilateral lucency (ie hypertransradiancy) due to
an area of reduced lung perfusion is well
described with massive pulmonary infarction. It is
a
very
rare
finding.
More
commonly
hypertransradiancy will have a technical cause
such as patient rotation1.
Question 10: Is there evidence of an
inhaled foreign body?
This patient had inhaled a peanut and attended
the Emergency Department. This CXR is
abnormal. It shows evidence of an obstructed
bronchus. An additional CXR was obtained,
following a particular manouvre, and that CXR
provided confirmation of the obstruction. The
peanut was removed.
The CXR analysis is provided on p. 30.
References
1. de Lacey G, Morley S, Berman L. The Chest X-Ray:
A Survival Guide. Saunders Elsevier; 2008.
2. Goodman LR. Felson's Principles of Chest
Roentgenology. 3rd ed. Saunders Elsevier; 2007.
3. Wipf JE, Lipsky BA, Hirschmann JV, et al.
Diagnosing pneumonia by physical examination:
relevant or relic? Arch Intern Med. 1999;159:1082–
1087.
4. Hansell DM, Lynch DA, McAdams HP, Bankier AA.
Imaging of Diseases of the Chest. 5th ed. Mosby
Elsevier; 2010.
5. Ball CG, Ranson K, Dente CJ, et al. Clinical
predictors of occult pneumothoraces in severely
injured blunt polytrauma patients: A prospective
observational study. Injury. 2009;40:44–47.
6. Jagannath AS, Sos TA, Lockhart SH, et al. Aortic
dissection: a statistical analysis of the usefulness of
plain chest radiographic findings. Am J Roentgenol.
1986;147:1123–1126.
7. Fisher ER, Stern EJ, Godwin JD, et al. Acute aortic
dissection: typical and atypical imaging features.
Radiographics. 1994;14:1263–1271.
8. Schnyder P, Wintermark M. Radiology of blunt
trauma of the chest. Springer-Verlag: Berlin; 2000.
9. Mirvis SE, Templeton PA. Imaging in acute thoracic
trauma. Semin Roentgenol. 1992;27:184–210.
10. Gavelli G, Canini R, Bertaccini P, et al. Traumatic
injuries: imaging of thoracic injuries. Eur Radiol.
2002;12:1273–1294.
11. Iyer VN, Joshi AY, Ryu JH. Spontaneous
pneumomediastinum: analysis of 62 consecutive
adult patients. Mayo Clin Proc. 2009;84:417–421.
19
Abdominal pain &
abdominal trauma
The AXR
Its usefulness 330
Best tests for specific clinical problems 331
Analysis: plain film checklists
Erect CXR 332
Supine AXR 333
The common problems
Non-specific abdominal pain 334
Suspected perforation 335
Suspected intestinal obstruction 336
Suspected constipation 337
Suspected renal colic 338
Infrequent but important problems
Blunt trauma to the abdomen 341
Penetrating injury to the abdomen 341
Appropriate imaging
▪ CT is frequently the optimum first line
investigation.
▪ US is sometimes the optimum first line test.
▪ The AXR has a limited, occasionally useful, role.
Abbreviations
AXR, abdominal X-ray examination;
CT, computed tomography;
CT KUB, computer tomographic examination of
the renal tract;
CXR, chest radiograph;
ED, Emergency Department, Emergency Room;
FAST, focussed abdominal sonography for trauma;
IVU, intravenous urogram;
US, diagnostic ultrasound/sonography.
The AXR—its usefulness
A patient with abdominal trauma does not require a plain
abdominal radiograph (AXR). The AXR will not contribute
to the clinical diagnosis and should be avoided.
The AXR is of limited value as a diagnostic tool in the
evaluation of many patients presenting with an acute
abdomen. This is largely because the abdominal contents
are composed of soft tissue. Plain film radiography does not
provide adequate soft tissue contrast discrimination to
detect and differentiate between many of the numerous
inflammatory and neoplastic intra-abdominal soft tissue
pathologies. The AXR is not the right tool for the job.
Consequently, it has been superseded by ultrasound and CT
scanning which are highly accurate in terms of evaluating
the various intra-abdominal soft tissues.
In present day clinical practice, the AXR is in the main
limited to confirming a clinical suspicion of large or small
bowel obstruction (as illustrated below), and demonstrating
dangerous swallowed foreign bodies. Even so, CT will be
selected as the first line imaging test in many cases of
suspected intestinal obstruction, and also as the preferred
and only imaging examination when renal colic is
suspected.
What if the preferrred imaging investigations are not
immediately available? Is there any point in requesting an
AXR as a substitute imaging test? On the whole, no. You
risk obtaining false reassurance from a seemingly normal
AXR appearance. It is safer to rely on a detailed clinical
history and a careful physical examination. Furthermore,
an experienced pair of examining hands from a member of
the surgical team will recognise the emergency case that
needs to go to theatre.
The table on the right indicates the relatively few
occasions when an AXR can be useful.
Distended small bowel. No large bowel gas.
Diagnosis: small bowel obstruction.
Gross distention of the large bowel extending
as low as the sigmoid colon. Diagnosis: large
bowel obstruction.
Radiology and abdominal pain
Analysis: plain film checklists
Erect CXR
In the context of a patient attending the Emergency
Department with abdominal pain there are just two
questions to ask of the CXR:
1. Does the erect CXR show any evidence of free air under
the diaphragm?
2. Is there any evidence of pneumonia?
This erect CXR shows: normal lung bases and
no free air under the diaphragm. The normal
appearance of each lung is described on pp. 308–
313.
Abdominal pain. No specific diagnostic features
from the history and clinical examination. The
erect CXR reveals an extensive pneumonia in the
right lower lobe.
Supine AXR
When analysing an AXR some normal features can be
listed:
▪ Gas within the stomach may be seen as gas outlining the
gastric folds in the left upper quadrant; there is rarely any
gas seen in the small bowel.
▪ Normal gas patterns in the colon and rectum will vary.
Sometimes segments of gas will be seen but no long
continuous segments that are distended.
▪ No calcification overlying the liver or gall bladder, nor
over the pancreas, kidney, ureters or urinary bladder.
▪ Calcification in the aorta may be age related and is
common in the elderly; it will not show any localised
bulge.
Supine AXR.
Normal features on this AXR: gastric folds/rugae
outlined; faeces in the ascending colon; no bowel
distension; no pathological calcification.
Supine AXR.
Elderly patient. Predominantly normal features
on this AXR. Gas in an undistended large bowel
(ascending, transverse, and descending colon);
some age related calcification in the aorta. (The
liver shadow might be prominent, but possible
hepatomegaly is better assessed on palpation
during the clinical examination.)
The common problems1-10
Both the likelihood of a particular diagnosis and the level of
clinical concern will determine the specific radiological
investigation that is selected. In some instances no imaging
will be requested. The local availability of equipment or
particular skills may also influence the choice of the first
line test.
The following descriptions refer solely to plain film
radiography; ie when a supine AXR or a CXR is obtained in
the Emergency Department.
Non-specific abdominal pain
An erect CXR is primarily obtained in order to exclude a
basal pneumonia or free air under the diaphragm. A supine
AXR is not a useful test, because:
▪ A normal AXR does not exclude serious pathology.
▪ A good clinical history and physical examination are more
useful than an AXR.
Following clinical examination the most useful imaging
tests are CT or ultrasound. In the absence of these
facilities, an AXR is unlikely to be better than the clinical
examination performed by an experienced member of the
surgical team.
Erect CXR. Extensive pneumonia in the left
lower lobe.
Erect CXR. Free air below both domes of the
diaphragm (arrows). The lung bases are clear.
Pneumonia diagnosis
Pneumonia is a well recognised cause of acute
abdominal pain, particularly in children. It might
be unwise to place too great a reliance on the
clinical examination of the chest alone as a means
of excluding a pneumonia. A prospective survey1
concluded:
“the traditional chest physical examination is
not sufficiently accurate on its own to confirm or
exclude the diagnosis of pneumonia”.
Suspected perforation
The most useful radiograph is a well-penetrated erect CXR.
An erect AXR is not indicated as the CXR is much more
reliable in detecting free air. Very small quantities (as little
as 1.0 ml) of free air can be demonstrated on an erect
CXR2.
If a patient is unable to sit up for an erect CXR then an
alternative technique is employed: the patient reclines in
the left-side-down decubitus position and a cross table AXR
is obtained using a horizontal X-ray beam.
Other options:
▪ In some centres in North America, CT is requested as the
first line investigation. CT is the most sensitive imaging
test for diagnosing pneumoperitoneum. It is highly
accurate, and it will often indicate the precise site of the
perforation.
▪ In a few centres sonography is utilized for the detection
of free intraperitoneal air3. Practitioners tend to follow a
step by step protocol. As follows: plain radiography first;
then ultrasound only in those in whom the plain
radiograph (usually an erect CXR) is normal. CT is thus
reserved for those occasions when ultrasonograhy still
fails to make the diagnosis6.
Suspected perforation. Patient too unwell to sit
up. A lateral decubitus AXR with the patient lying
on the left side. A large amount of free
intraperitoneal air is shown (between the
arrowheads) above the lateral surface of the liver.
The air outlines the undersurface of the right
dome of the diaphragm (arrows).
Suspected intestinal obstruction
The options:
1. CT.
CT is highly accurate in demonstrating or excluding
obstruction4,5. In addition, the precise site and probable
cause of the obstruction can usually be defined. In an
individual patient, the surgical team may well prefer CT
as the first line imaging test, because of the excellent
detail and additional information that will be provided.
2. Supine AXR.
Some basic features will assist with diagnosis.
□ Dilated small bowel with an absence of colon gas
suggests a complete, or a nearly complete mechanical
obstruction to the small bowel.
□ Dilated small bowel with gas in an undistended colon
suggests either an incomplete mechanical obstruction
to the small bowel, or a localised adynamic (ie
paralytic) ileus.
□ Dilated large bowel but no small bowel dilatation
suggests mechanical obstruction to the large bowel
with a competent ileo-caecal valve.
□ Dilated large bowel with dilated small bowel suggests
either mechanical large bowel obstruction with an
incompetent ileo-caecal valve, or a generalized
adynamic (ie paralytic) ileus. The distinction is usually
clinically obvious.
Pitfalls.
The supine AXR may appear normal—to the
inexperienced observer—in two circumstances:
1. A very high small bowel obstruction.
2. Very occasionally the obstructed small bowel
will distend with fluid and not with gas.
Consequently there will not be the usual
finding of multiple loops of bowel distended
with gas.
Colicky abdominal pain.
Dilated loops of small bowel (arrows). Some loops
measure 50 mm in diameter (the upper limit of
normal is 30 mm). Almost no gas within the large
bowel. Mechanical small bowel obstruction.
Colicky abdominal pain.
Transverse colon and descending colon are
dilated (arrowheads). A small amount of gas in
the distal sigmoid. The caecum and ascending
colon are also distended and contain faecal
residue (arrows). These findings indicate a high
grade mechanical obstruction in the distal
descending colon or in the sigmoid colon. The
absence of small bowel dilatation is due to a
competent ileo-caecal valve. If the obstruction
persists, then the small bowel will eventually
become distended with gas.
Suspected constipation
The plain AXR is rarely of help in reaching a diagnosis of
constipation as being the likely cause of abdominal pain.
Because:
▪ The clinical history in relation to a change in stool
frequency and consistency, together with a rectal
examination, is usually diagnostic.
▪ The normal quantity of formed stool in the colon varies
from person to person. A subjective quantification on the
basis of the AXR appearances can be erroneous.
Suspected renal colic
The options:
1. Unenhanced multidetector CT, often referred to as a CT
KUB.
The CT KUB is now established as the preferred imaging
test when renal colic is suspected5–9. It is an accurate and
quick examination and there is no need for intravenous
contrast medium injection.
2. Sonography.
A case has been made that in female patients presenting
with flank pain and suspected renal colic, sonography
should be the initial examination in order to detect the
presence of hydronephrosis6. This alternative approach is
(a) based on consideration of the CT radiation dose to the
ovaries and (b) because sonography is so good at
detecting other pathologies deep in the female pelvis
that may account for the patient's symptoms.
3. AXR plus sonography.
Others have suggested that patients should have an AXR
and ultrasound as a combination examination and if
negative that CT should be reserved for the patient who
does not subsequently improve on conservative
management10. The addition of the AXR has been found
to improve the accuracy of diagnosis of renal colic,ie
when compared with ultrasound as the solitary
examination10.
4. Limited intravenous urography.
Carried out as a two film examination: A plain AXR will
be diagnostic when there is an obvious opaque calculus
in the line of the renal tract. It is less helpful if the film
(image) appears normal. A calculus might be obscured by
superimposed bone, or confused with a pelvic phlebolith,
or might simply be insufficiently radio-opaque to be seen.
Although 90% of renal calculi contain calcium, less than
50% are visible on an AXR. Consequently, a single
additional AXR at 10 minutes after the intravenous
injection of contrast medium will be highly accurate in
confirming or excluding the presence of a ureteric
calculus. Normal excretion of the contrast medium
together with undilated calyces and ureter will exclude
the diagnosis of renal colic; delay in excretion on the
painful side and/or calyceal/ureteric dilatation will
confirm the diagnosis of renal colic.
Clinical suspicion: acute left sided ureteric
colic.
The patient was referred directly for a CT
examination. The obstructing calculus in the
lower third of the ureter is shown on this coronal
reconstruction.
Clinical suspicion: acute left sided ureteric
colic. Faint calcification in the true pelvis was
seen on the supine AXR. This single radiograph
obtained 10–20 minutes after the injection of
contrast medium confirms that a calculus is
causing ureteric obstruction.
Suspected acute biliary disease
Sonography is the first line imaging procedure whenever
the suspicion is that of biliary colic or gall bladder disease.
Suspected abdominal aortic
aneurysm/rupture
Sonography is the first line investigation.
Suspected foreign body ingestion
The important roles of the CXR, the AXR and hand held
metal detector scanning are described in Chapter 21
(Swallowed Foreign Bodies).
Infrequent but important problems
Blunt trauma to the abdomen
In patients who have sustained abdominal or pelvic trauma
the rapid assessment of the injury is critical. Delay
increases mortality and morbidity11.
▪ Plain abdominal radiography is not indicated when
investigating a blunt or penetrating injury. Obtaining an
AXR is strongly discouraged—it delays the useful
investigations.
▪ Recommendations in relation to imaging11:
□ Haemodynamically stable patient: the need is to
demonstrate or exclude an intra-abdominal injury. CT
is the examination of choice.
□ Haemodynamically unstable patient: the need is to
establish that the assumed bleeding is intraabdominal. A FAST ultrasound examination is
indicated. This test can be performed very quickly. If
free fluid (blood) is detected then the patient can
proceed to theatre for surgery.
Focussed abdominal sonography for
trauma (FAST).
FAST is an abbreviated and protocol-designated
form of ultrasound assessment that seeks only to
demonstrate
whether
intraperitoneal
or
pericardial fluid is present or is increasing. It
does not seek to define the exact site of injury.
Carrying out a FAST study (after appropriate
training) has been shown to be well within the
capabilities of residents and registrars working in
the Emergency Department12–14.
Penetrating injury to the abdomen
▪ Haemodynamically stable patient: If the surgeon does not
elect to proceed immediately to surgery for wound
exploration then CT is the most useful imaging test. CT
will demonstrate organ damage.
▪ Haemodynamically unstable patient: requires immediate
surgery not imaging.
References
1. Wipf JE, Lipsky BA, Hirschmann JV, et al.
Diagnosing pneumonia by physical examination:
relevant or relic? Arch Intern Med. 1999;159:1082–
1087.
2. Miller RE, Nelson SW. The Roentgenologic
demonstration of tiny amounts of free
intraperitoneal gas: experimental and clinical
studies. Am J Roentgenol. 1971;112:574–585.
3. Chen SC, Yen ZS, Wang HP, et al. Ultrasonography
is superior to plain radiography in the diagnosis of
pneumoperitoneum. Br J Surg. 2002;89:351–354.
4. Smith JE, Hall EJ. The use of plain abdominal X rays
in the emergency department. Emerg Med J.
2009;26:160–163.
5. Maglinte DDT, Kelvin FM, Rowe MG, et al. Small
bowel obstruction: optimizing radiologic
investigation and non-surgical management.
Radiology. 2001;218:39–46.
6. Patatas K, Panditaratne N, Wah TM, et al.
Emergency Department imaging protocol for
suspected acute renal colic: re-evaluating our
service. Brit J Radiol. 2012;85:1118–1122.
7. Kennish SJ, Bhatnagar P, Wah TM, et al. Is the KUB
radiograph redundant for investigating acute
ureteric colic in the non-contrast enhanced
computed tomography era? Clin Rad. 2008;63:1131–
1135.
8. The Royal College of Radiologists. iRefer: Making
the best use of clinical radiology. The Royal College
of Radiologists: London; 2012
http://www.rcr.ac.uk/content.aspx?PageID=995.
9. British Association of Urological Surgeons (BAUS)
guidelines for acute management of first
presentation of renal/ureteric lithiasis.
http://www.bauslibrary.co.uk/PDFS/BSEND/Stone_G
uidelinesDec2008pdf; 2008.
10. Ripolles T, Agramunt M, Errando J, et al. Suspected
ureteral colic: plain film and sonography Vs
unenhanced helical CT. A prospective study in 66
patients. Eur Radiol. 2004;14:129–136.
11. Jansen JO, Yule SR, Loudon MA. Investigation of
blunt abdominal trauma. BMJ. 2008;336:938–942.
12. Lingawi SS, Buckley AR. Focused abdominal US in
patients with trauma. Radiology. 2000;217:426–429.
13. Weishaupt D, Grozaj AM, Willmann JK, et al.
Traumatic injuries: imaging of abdominal and pelvic
injuries. Eur Radiol. 2002;12:1295–1311.
14. Ingeman JE, Plewa MC, Okasinski RE, et al.
Emergency physician use of ultrasonography in
blunt abdominal trauma. Acad Emerg Med.
1996;3:931–937.
20
Penetrating foreign bodies
Appearances on plain radiographs
Glass 344
Metal 344
Wood or plastic 344
Soft tissue laceration
Foreign body detection 346
Imaging pitfalls 346
Foreign body removal 347
Orbital injury
Foreign body detection 347
Orbital radiography 348
Foreign body removal 348
The standard radiographs
Foreign body in soft tissue
▪ Two radiographs—angulated so that bone does
not obscure the injured site.
Orbital foreign bodies
▪ Two frontal projections: upward and downward
gaze.
Alternative imaging to consider
Soft tissue foreign bodies
▪ Superficial: sonography.
▪ Deeply penetrating: CT or MRI.
Orbital foreign bodies
▪ CT or MRI.
Regularly overlooked foreign
bodies
▪ Glass hidden by bone.
▪ Deeply penetrating FBs.
Abbreviations
CT, computer tomography;
FB, foreign body;
MRI, magnetic resonance imaging;
PA, posterior-anterior.
Appearances on plain radiographs
Glass
All glass is radio-opaque. Visibility of glass is not dependent
on its lead content1,2.
The radiographic density of the different types of glass
does vary. Imaging technique is important. A soft tissue
exposure is essential.
Zooming on a digital image is often necessary, otherwise
very small fragments are easily overlooked.
Metal
Most metals are radio-opaque. A notable exception is
aluminium.
Wood or plastic
Only occasionally will wood be visualised3–5. A splinter
might be well defined on a radiograph if the fragment has
paint on its surface.
Why is wood almost non-opaque on a radiograph?
▪ Explanation: the detection of a foreign body is
dependent on the atomic numbers of its constituent atoms
in contrast to those of human soft tissue. Wood and soft
tissue are both largely composed of carbon and other
atoms with similar, low, atomic numbers. Therefore they
are not readily differentiated by the X-ray beam.
In clinical practice it is best to assume that all splinters,
thorns, and fragments of plastic will be non-opaque on a
radiograph.
This splinter of wood was only visible because it
had a thick coat of paint on its surface. It is
usually very difficult to visualise wooden splinters
or thorns on a radiograph.
Wood splinters are often invisible, or barely
visible, on a radiograph. On the left, a wood
splinter (arrow); on the right, a toothpick (arrow).
Visibility of penetrating foreign bodies. The top
left image shows four different foreign bodies
covered by soft tissue (turkey meat). The glass
shard is from a broken picture frame. The top
right image shows three other foreign bodies
covered by turkey meat. All are invisible. The
bottom image shows two pieces of glass buried in
the soft tissues of a shoulder of lamb. Note that
bone overlies part of one piece of glass and it is
that portion of the fragment that is most difficult
to visualise.
Suspected foreign bodies
Soft tissue laceration 6–8
Foreign body detection
First choice in the Emergency Department: plain
radiography.
□ Glass and metals (except for aluminium) well visualised.
□ Wood, plastic and aluminium not visualised.
Back up options in specific cases:
▪ Sonography (ultrasound).
□ Glass, metal, wood and plastic well visualised.
□ But… operator dependent, and will detect superficial
foreign bodies only.
▪ CT.
□ Most foreign bodies are well visualised.
□ Wood can be difficult to visualise.
▪ MRI.
□ Wood shows up well.
□ A risky investigation if a foreign body is
ferromagnetic.
Imaging pitfalls: Glass and metallic foreign
bodies2,3,8,9
▪ Pitfall (1): Overlying bone on a radiograph will
hide/obscure glass fragments including very dense shards.
Project the site of injury away from bone. Two or more
projections are required.
▪ Pitfall (2): If there has been high energy trauma, such as
a fall from a height, a glass foreign body may be driven
deep into the tissues and well away from the laceration.
The precise history and circumstance in relation to the
glass injury will determine if the radiographic field needs
to be extended well beyond the laceration.
▪ Pitfall (3): With gun shot wounds the bullet (if there is
no exit wound) can be situated far from the entry point. A
wide radiographic field may need to be covered. On
occasion, fluoroscopy can be helpful when searching for a
missing bullet that has not been located on the original
radiographs.
Glass wound to the face.
The left hand image shows the pointer indicating
the site of the wound—but there is no evidence of
a glass foreign body. The second image was taken
with the maxilla rotated away from the site of
injury, revealing a glass foreign body (arrow). Be
careful: overlying bone will obscure or hide a
glass foreign body.
Foreign body removal
Prior to surgical exploration it will sometimes be helpful if
the precise position of a glass fragment or wooden splinter
is shown beneath the skin. In these instances sonography
can provide guidance at the time of removal. If a foreign
body is situated deep in the soft tissues and sonography
cannot provide the required information, then CT or MRI
will often provide excellent localisation.
Orbital injury
Foreign body detection10,11
Most foreign bodies will be detected with slit lamp
ophthalmoscopy.
Plain radiography, ultrasound, or CT will be of assistance
in selected cases.
▪ Glass or metal fragments
Plain film radiography is recommended.
▪ Wood or plastic fragments
Sonography is recommended. The accuracy of detection is
dependent on an experienced operator and the quality of
the equipment. CT is an alternative to ultrasound and is
the preferred investigation in some centres. CT is
sensitive, shows the retrobulbar space better than
ultrasound, and is less operator-dependent10. MRI is also
available. It can be utilised when CT findings are
uncertain11. A history of a ferromagnetic foreign body
injury to the orbit is a contraindication to a MRI
examination.
Orbital radiography.
Two frontal projections: downward gaze (top left)
and then upward gaze (top right). Movement (or
lack of movement) of a fragment on upward and
downward gaze will indicate whether it is
situated within or outside the globe.
CT is available should there be any lack of
certainty as to the position of a foreign body after
the plain films have been scrutinised. The CT
image shown on the right is of a different patient.
Foreign body removal
Ultrasound or CT can provide accurate localisation prior to
exploration of the orbit10.
References
1. Tandberg D. Glass in the hand and foot. Will an Xray film show it? JAMA. 1982;248:1872–1874.
2. de Lacey G, Evans R, Sandin B. Penetrating injuries:
how easy is it to see glass (and plastic) on
radiographs? Br J Radiol. 1985;58:27–30.
3. Hunter TB, Taljanovic MS. Foreign Bodies.
Radiographics. 2003;23:731–757.
4. Peterson JJ, Bancroft LW, Kransdorf MJ. Wooden
Foreign Bodies. Am J Roentgenol. 2002;178:557–
562.
5. Horton LK, Jacobson JA, Powell A, et al. Sonography
and Radiography of soft tissue Foreign Bodies. Am J
Roentgenol. 2001;176:1155–1159.
6. Ginsburg MJ, Ellis GL, Flom LL. Detection of softtissue foreign bodies by plain radiography,
xerography, computed tomography, and
ultrasonography. Ann Emerg Med. 1990;19:701–703.
7. Gilbert FJ, Campbell RS, Bayliss AP. The role of
ultrasound in the detection of non-radiopaque
foreign bodies. Clin Radiol. 1990;41:109–112.
8. Wilson AJ. Gunshot injuries: what does a Radiologist
need to know? Radiographics. 1999;19:1358–1368.
9. Boyse TD, Fessell DP, Jacobson JA, et al. US of soft
tissue foreign bodies and associated complications
with surgical correlation. Radiographics.
2001;21:1251–1256.
10. Etherington RJ, Hourihan MD. Localisation of
intraocular and intraorbital foreign bodies using
computed tomography. Clin Radiol. 1989;40:610–
614.
11. Kubal WS. Imaging of orbital trauma.
Radiographics. 2008;28:1729–1739.
21
Swallowed foreign bodies
The most common foreign bodies
Children: coins 350
Adults: fish bones 352
Infrequent but important foreign bodies
Sharp objects other than fish bones 356
Button batteries 358
Magnets 359
Large objects—dentures 360
Hard plastic clips 361
Bezoars 361
Dangerous injuries
▪ Coins may lodge in the oesophagus—slightly
dangerous.
□ The CXR must include the neck.
▪ Button batteries may lodge in the oesophagus—
highly dangerous.
□ The halo sign is important.
▪ Two magnets in the bowel—highly dangerous.
□ Use of a compass may be crucial.
Useful tools
▪
▪
▪
▪
X-ray machine.
Hand held metal detector.
A compass.
CT Scanner.
Abbreviations
AXR, abdominal radiograph;
BB, button battery;
CXR, chest radiograph;
ED, Emergency Department;
FB, foreign body;
HHMD, hand held metal detector.
The most common foreign bodies1
Children: coins
Radiography…
▪ An AP chest radiograph (CXR) to include all of the neck
below the angle of the mandible.
▪ An abdominal radiograph (AXR) is not indicated2,3.
Occasionally, a coin will lodge in the oesophagus. Some of
these patients will be asymptomatic. An unrecognised coin
can cause clinical problems including erosion of the
mucosa which may result in an abscess or mediastinitis4. It
is important to confirm that any swallowed coin has passed
beyond the oesophagus. If the CXR is clear then the
parents can be reassured that the coin will be passed
within a few days.
Does the stool need to be checked? Sometimes a coin will
be overlooked in the stool; the parents would be better
advised to return to the Emergency Department (ED) only
if the child becomes symptomatic.
Coin composition: coins in the UK and in the European
Union are made of steel or alloys of various metals and
sometimes coated with copper. In effect, these coins are
inert. This does not apply worldwide. For example, in 1982
because of the cost of copper the one cent coin in the USA
(commonly referred to as the penny) was minted with a
mainly zinc core and a thin copper coating. Interaction
between gastric acid and zinc can cause ulceration in the
stomach. This possibility led to various scares and the
consequent overuse of routine AXR. The penny constituents
were
not
changed,
but
eventually
a
practical
recommendation was made and widely adopted: if a USA
penny has been swallowed and the CXR is clear then an
AXR need only be obtained in a child who subsequently
developes intestinal symptoms. The latter is an
exceptionally rare occurrence.
Hand held metal detector (HHMD)
scanning5–7
Consider this as an alternative to radiography.
Advantages of a HHMD include:
▪ It eliminates the need for a CXR.
▪ There is no ionizing radiation.
▪ It is accurate and easy to use with minimal
training.
▪ Patient and parent time spent in the ED is
reduced.
▪ It is cost effective.
▪ Its efficacy is underpinned by a tried and tested
diagnostic algorithm.
Pitfall. If using a HHMD, a definite history in
relation to the swallowed foreign body being a
coin is most important. If the history is uncertain
and the foreign body could be a magnet or a
cluster of magnets (see p. 359) then a false
reassurance might be provided by the HHMD. A
safety net: concern regarding a cluster of
magnets masquerading as a swallowed coin can
be eliminated by passing a compass over the
abdomen8. The lack of compass movement will
exclude a magnet.
Pitfall (1). Two swallowed coins can lodge
together at the same level in the oesophagus. The
coins can overlap each other and appear as a
single foreign body on the frontal CXR. A lateral
CXR will demonstrate whether one or two coins
are impacted.
Pitfall (2). The majority of retained coins are
situated in the upper oesophagus9–11 at the level
of the cricopharyngeus muscle. An impacted coin
can be missed if the whole neck below the level of
the angle of the mandible is not included on the
CXR.
In this child the coin is only just included on the
radiograph. The cardinal rule has not been
followed…
“The CXR must include all of the neck below
the angle of the mandible”.
Adults: fish bones
Fish bones comprise more than 70% of all foreign body
events that cause an attendance to some EDs12,13.
Complications resulting from an impacted fish bone are
rare but can be serious. These include: neck abscess,
mediastinitis and lung abscess.
Fish bone impaction is very different to that of other
impacted foreign bodies14,15.
▪ Infrahyoid impaction is much less frequent. In one
series15 approximately 90% of fish bones were situated in
the oro-pharynx, whereas approximately 90% of other
foreign bodies (poultry bones, dentures, wood splinters,
coins, pork bones and lamb bones) were impacted more
distally in the laryngeal pharynx or upper oesophagus.
Radiography.
▪ The soft tissues of the oro-pharynx and down to the level
of the hyoid bone are dense on the lateral radiograph. A
lateral neck radiograph will rarely detect a fish bone
impacted in these dense areas.
▪ The use of a lateral radiograph of the neck should be
limited, selectively employed, and based on a diagnostic
algorithm (see p. 353).
What to look for.
▪ The occasional fish bone that does impact below the
hyoid bone.
▪ Evidence of a complication:
□ Gas in the soft tissues, either as a streak or as a
pocket, suggests perforation.
□ Widening of the prevertebral soft tissues suggests an
abscess.
Different fish bones have different
radiographic densities14,16,17:
▪ Readily visible: cod, haddock, cole fish, lemon
sole, gurnard.
▪ More difficult to see: grey mullet, plaice,
monkfish, red snapper.
▪ Not visible: herring, kipper, salmon, mackerel,
trout, pike.
Normal prevertebral soft tissue width:
▪ Above C4 vertebra: up to 7 mm.
▪ Below C4 vertebra: up to 22 mm.
Fish bones. What to look for.
Check that the prevertebral soft tissue widths are
within normal limits (left).
Look for a fish bone: faintly visible (arrow)
anterior to the C6 vertebra (right).
A protocol for suspected fish bone
impaction
1. Oro-pharynx examined with illumination.
The vast majority of impacted fish bones will be
visible. No radiography required.
2. If the fish bone is not seen in the oro-pharynx,
then the next steps will depend on the level of
clinical concern and on local guidelines.
Possibilities:
□ Request a lateral radiograph of the neck.
Apply this rule: If the radiograph is normal
and the patient is considered well enough to
be sent home, then the patient should be told
to re-attend the next day if symptoms are
persisting. Patients who re-attend should be
seen immediately by an ear, nose and throat
specialist.
□ Or… direct referral for endoscopy.
□ Or… request CT of the neck.
Compared with impacted fish bones the
tendency is for chicken bones to lodge at a
somewhat lower level. This chicken bone (arrow)
is impacted at the C7–T1 level.
Laryngeal and cricoid cartilages can ossify
partly or almost entirely. There is no fixed
pattern.
Partial ossification can lead to a false positive
diagnosis of an impacted bone. Similarly an
impacted bone may be dismissed as a partly
ossified cartilage.
Careful analysis and linking that analysis to the
clinical history is most important.
Beware. Normal calcifications and
ossifications.
(a) Calcified stylo-hyoid ligament (arrowheads).
Calcification (arrows) in relation to the anterior
longitudinal ligament of the cervical spine.
(b) Calcification at the C6–C7 level (arrow) is
ossification in the posterior aspect of the cricoid
cartilage.
(c) Ossification in the triticeous cartilage
(arrow); in the thyroid cartilage (arrowhead); in
the cricoid cartilage (asterisk).
(d) Very extensive ossification/calcifications in
the hyoid bone, the laryngeal cartilage, the
cricoid cartilage, and in several tracheal rings.
Infrequent but important FBs
Sharp objects other than fish bones
Many sharp objects pass through the intestines without
causing a problem. Nevertheless a sharp or pointed object
may penetrate the oesophagus or the bowel. The presence
of the swallowed object needs to be confirmed (or
excluded).
Radiography:
▪ For metallic foreign bodies such as nails, needles, screws
or razor blades a CXR and an AXR are indicated.
▪ For chicken, pork chop18, or lamb bones a lateral view of
the neck is indicated. Approximately 90% of these foreign
bodies, when impacted, will be found to be lodged in the
hypopharynx or upper oesophagus15. This is a very
different position of impaction as compared with impacted
fish bones (see pp. 352–353).
▪ Wood and plastic foreign bodies are radiolucent and will
not be identified on a radiograph. If clinical suspicion is
high (eg a swallowed and impacted pencil or toothpick)
then CT, or a contrast medium swallow, or endoscopy, will
be indicated.
▪ Aluminium (eg as in a drink can ring pull) is of very low
radiodensity19 and is rarely detectable on a radiograph. An
aluminium ring pull (aka aluminium tab) will be detected
by a HHMD5–7. Many countries have largely overcome the
swallowed ring pull problem by producing ring pulls that
remain attached to the can after the can is opened.
Nevertheless, it is still possible to detach the ring pull
from the can by wiggling it. Therefore the swallowing of
ring pulls has not been eliminated entirely20.
An AXR must be obtained whenever a sharp
metallic object might have been swallowed.
A case of habitual foreign body ingestion. Four
metallic foreign bodies are shown. The needle
places the patient at risk of a perforation.
Be wary—the orientation of a foreign
body can mislead.
Impacted chicken bone.
On presentation (far left) the bone (arrowhead)
lay in a horizontal position and was not
recognised.
Several days later (left) the bone lay vertically
and is very easy to identify. Note the soft tissue
swelling and faint bubbles of gas indicating an
abscess around a perforation1.
Why is a bowel perforation relatively
infrequent?10,21
90% of swallowed foreign bodies pass through
the intestine without any problem, and this
includes many nails and razor blades.
Sharp metallic foreign bodies rarely perforate
the bowel wall. The intestine resists perforation
and laceration partly because it is lined with
mucus, is very pliable, and when a sharp FB
reaches the colon it becomes encased with
faeces.
Travelling head first: a pin or needle will often
pass through the intestine with the blunt end
leading21,22. It has been suggested that ingested
needles and pins tumble and turn until the blunt
end faces forwards!
When perforations do occur they may be silent.
A needle lying in the soft tissues outside of the
bowel may be discovered years later on an AXR
obtained for other reasons21.
Button batteries23–27
An impacted button battery (BB) is a diagnostic and
endoscopic emergency. If ingested, a CXR is crucial. Obtain
it as soon as the patient arrives in the ED.
Most small size BB ingestions do not cause damage,
provided the BB does not lodge in the oesophagus. The
frequency of lodgement is increasing with widespread
usage of the 20–25 mm diameter lithium batteries. A BB
stuck in the oesophagus can cause serious mucosal injury.
The damage is primarily caused by an electrical current
that hydrolyzes soft tissue and results in liquefactive
necrosis, not leakage of battery contents. Damage can
occur very quickly, sometimes within one or two hours of
lodgement23,24. Mucosal damage can result in oesophageal
perforation, tracheoesophageal fistula, stricture formation,
and death24. Rapid diagnosis and emergency removal of a
lodged battery is essential.
Note: BBs can also cause a similarly serious injury if
placed in the ear or nose23,24,27.
Those unfamiliar with the appearance of a BB
on an AP CXR should look for the double rim or
halo appearance of a BB as compared with the
appearance of a small coin (ie no halo). This halo
appearance is unique to a BB. The right hand
image is a radiograph of a coin and a BB seen en
face in ultrasound gel (soft tissue).
Pitfalls.
1. Unwitnessed ingestions in children are
common and BB lodgement may initially
cause non-specific symptoms. A high index of
suspicion is necessary in those patients who
are puzzlingly unwell and who may be prone
to swallowing foreign bodies—ie little
children.
2. If the CXR for a suspected foreign body does
not include all of the neck below the angle of
the mandible, a BB lodged high in the
oesophagus can be missed.
3. A BB shown on a CXR can be misread as a
coin or, occasionally, read as an external
object such as an ECG electrode23. It is
essential that those working in the ED always
check whether or not any foreign body or
metallic density overlying the oesophagus
shows the incontrovertibly diagnostic halo
sign.
Magnets6,10–12,28
Powerful rare earth magnets can be found in toys, jewellery
items, beads, nose and tongue piercings, studs, desk toys,
stress relievers, homeopathic and naturalistic aids, and
other items such as bracelets used in folk medicine.
Swallowing magnets appears to be relatively common
amongst autistic children with access to magnetic pieces8.
The ED aim is to determine whether more than one
magnet has been swallowed. If a child swallows more than
one magnet and they pass through the pylorus then the
separate pieces can attract each other across different
bowel loops. Gut wall necrosis, perforation, fistulae,
haemorrhage, and volvulus are potential and serious
consequences. Alternatively, a child might swallow one
magnet and another piece of metal to which it is attracted.
This is also dangerous.
Small rare earth magnets are enormously
powerful.
Two or more magnets in the bowel are highly
dangerous.
Pitfalls.
1. On the AXR a cluster of magnets clumped
tightly together across different bowel loops
can be misread as a harmless necklace or
other single object. Avoid this risk by putting
a compass against the patient's abdomen8. If
the compass indicates the object is a cluster
of magnets, then it represents a surgical
emergency.
2. Detection using a metal detector (p. 350)
poses a similar risk. If there is uncertainty as
to what has been swallowed, then a magnet
detected by a HHMD might be assumed,
erroneously, to be a coin. Placing a compass
against the abdomen will assist. Lack of
compass movement will exclude a magnet.
Large objects—dentures29–31
Radiographic appearance of dentures
▪ Methylmethacrylate is the acrylic plastic from
which most dentures are constructed. It is
radiolucent.
▪ Some, but not all, dentures will contain metal
as a fixing or support and consequently will be
radiographically visible when impacted31.
▪ Note: Porcelain and plastic teeth are of very low
radio-density30.
A large object such as a dental plate or appliance may
lodge in the cervical or thoracic oesophagus. If it remains
impacted it may erode the mucosa and cause an abscess or
mediastinitis. Radiography:
1. Well penetrated PA and lateral CXR, to include the neck.
2. If these images are normal, an AXR should be obtained.
3. If this image is normal, and the clinical history or
symptoms remain suggestive, a barium swallow or
endoscopy will be necessary.
A negative CXR does not exclude an impacted denture;
not all dentures are radio-opaque.
Ingestion risk is not limited to partial dentures. Full (ie
complete) dentures can be swallowed.
CT and MRI can help to identify acrylic dentures.
However, image interpretation with these investigations is
not always straightforward and can be very difficult30.
Denture impacted in the lower oesophagus. It
was not identified on the frontal CXR. This lateral
view was essential.
Hard plastic clips
Bread bag clip ingestion can cause intestinal perforation,
stricture, or obstruction.
▪ Some countries have eliminated these bread bag clips
and replaced them with tape; others have altered the
design of the clip; others may still use these clips.
▪ The impaction mechanism is seemingly due to the
prolapse of mucosa into the jaws of the clip. This
impaction can erode the mucosa32. Complications from an
impaction may be delayed and can occur years after the
ingestion. Most cases of accidental ingestion of a bread
bag clip occur in elderly and edentulous patients. The
patient is usually unaware of having ingested this foreign
body.
▪ Strong plastic bread bag clips are radiolucent and will
not be detectable on a radiograph. The contribution from
radiology is limited to providing assistance with the
diagnosis of complications that may occur such as
perforation or intestinal obstruction.
Bezoars33
A bezoar is ingested foreign material that accumulates
within the gastrointestinal tract.
▪ The most frequent bezoars are phytobezoars (poorly
digested fruit and vegetable fibres) and trichobezoars
(ingested hair). Phytobezoars are the most common.
▪ Frequently there is a history of previous gastrointestinal
surgery.
▪ Intestinal obstruction is a recognized complication.
Radiography:
▪ In general, plain film radiography is unhelpful (in
diagnosing the likely cause) when a patient presents with
bezoar induced intestinal obstruction.
▪ On the other hand, sonography or CT can assist with the
rapid diagnosis of a bezoar as the cause of the intestinal
obstruction33.
References
1. Remedios D, Charlesworth C, de Lacey G. Imaging
of foreign bodies. Imaging. 1993;5:171–179.
2. Swallowed coins. Editorial. Lancet. 1989;2:659–660.
3. Stringer MD, Capps SN. Rationalising the
management of swallowed coins in children. Br Med
J. 1991;302:1321–1322.
4. Nahman B, Mueller CF. Asymptomatic oesophageal
perforation by a coin in a child. Ann Emerg Med.
1984;13:627–629.
5. Lee JB, Ahmad S, Gale CP. Detection of coins
ingested by children using a hand held metal
detector: a systematic review. Emerg Med J.
2005;22:839–844.
6. Seikel K, Primm PA, Elizondo BJ, Remley KL. Handheld metal detector localisation of ingested metallic
foreign bodies; accurate in any hands? Arch Pediatr
Adolesc Med. 1999;153:853–857.
7. Ramlakhan SL, Burke DP, Gilchrist J. Things that go
beep: experience with an ED guideline for use of a
HHMD in the management of ingested nonhazardous metallic foreign bodies. Emerg Med J.
2006;23:456–460.
8. CDC. Gastrointestinal injuries from magnet
ingestion in children. United States, 2003–2006.
MMWR. 2006;55:1296–1300.
9. Koirala K, Rai S, Shah R. Foreign Body in the
esophagus: comparison between adult and pediatric
population. Nepal J of. Med Sci. 2012;1:42–44.
10. Hunter TB, Taljanovic MS. Foreign Bodies.
Radiographics. 2003;23:731–757.
11. Chung S, Forte V, Campisi P. A review of pediatric
foreign body ingestion and management. Clin Pediat.
Emerg Med. 2010;11:225–230.
12. Nandi P, Ong GB. Foreign body in the oesophagus:
review of 2394 cases. Br J Surg. 1978;65:5–9.
13. Lue AJ, Fang WD, Manolidis S. Use of plain
radiography and computed tomography to identify
fish bone foreign bodies. Otolaryngol Head Neck
Surg. 2000;123:435–438.
14. Ritchie T, Harvey M. The utility of plain radiography
in assessment of upper aerodigestive tract fishbone
impaction: an evaluation of 22 New Zealand fish
species. NZ Med J. 2010;123:32–37.
15. O’Flynn P, Simo R. Fish bones and other foreign
bodies. Clin Otolaryngol Allied Sci. 1993;18:231–
233.
16. Ell SR, Sprigg A, Parker AJ. A multi-observer study
examining the radiographic visibility of fishbone
foreign bodies. J R Soc Med. 1996;89:31–34.
17. Davies WR, Bate PJ. Relative radio-opacity of
commonly consumed fish species in South East
Queensland on lateral neck X-ray: an ovine model.
Med J Aust. 2009;191:677–680.
18. Liu J, Zhang X, Xie D, et al. Acute mediastinitis
associated with foreign body erosion from the
hypopharynx and esophagus. Otolaryngol Head
Neck Surg. 2012;146:58–62.
19. Valente JH, Lemke T, Ridlen M, et al. Aluminium
foreign bodies: do they show up on X-Ray? Emerg
Radiol. 2005;12:30–33.
20. Donnelly LF. Beverage can stay-tabs: still a source
for inadvertently ingested foreign bodies in children.
Pediatr Radiol. 2010;40:1485–1489.
21. Rahalkar MD, Pai B, Kukade G, Al Busaidi SS.
Sewing needles as foreign bodies in the liver and
pancreas. Clin Rad. 2003;58:84–86.
22. Ward A, Ribchester J. Migration into the liver by
ingested foreign bodies. Br J Clin Pract.
1978;32:263.
23. Litovitz T, Whitaker N, Clark L, et al. Emerging
battery ingestion hazard: clinical implications.
Pediatrics. 2010;125:1168–1177.
24. Lee SL. Recognition of esophageal Disc battery on
Roentgenogram. Arch Otolaryngol Head Neck Surg.
2012;138:193–195.
25. Litovitz T, Whitaker N, Clark L. Preventing battery
ingestions: an analysis of 8,648 cases. Pediatrics.
2010;125:1178–1183.
26. Litovitz T, Schmitz BF. Ingestion of cylindrical and
button batteries: an analysis of 2382 cases.
Pediatrics. 1992;89:747–757.
27. Premachandra DJ, McRae D. Severe tissue
destruction in the ear caused by alkaline button
batteries. Postgrad Med. 1990;66:52–53.
28. Oestreich AE. Danger of multiple magnets beyond
the stomach in children. J Nat Med Assoc.
2006;98:277–279.
29. Hashmi S, Walter J, Smith W, Latis S. Swallowed
partial dentures. J R Soc Med. 2004;97:72–75.
30. Haidary A, Leider JS, Silbergleit R. Unsuspected
swallowing of a partial denture. Am. J Neuroradiol.
2007;28:1734–1735.
31. Abu Kasim NH, Abdullah BI, Mahadevan I, Yunus N.
The radio-opacity of dental prostheses (fixed and
removeable) on plain radiographs—an experimental
study. Annals Dent Univ Malaya. 1998;5:35–39.
32. Morrissey SK, Thakkar SJ, Weaver ML, Farah K.
Bread Bag Clip ingestion. Gastroenterol Hepatol
(NY). 2008;4:499–500.
33. Ripolles T, Garcia-Aguayo J, Martinez MJ, Gil P.
Gastrointestinal bezoars. Sonographic and CT
characteristics. Am J Roentgenol. 2001;177:65–69.
22
Test yourself
Assess the radiographs in this chapter to test
your knowledge and diagnostic skills.
Each patient attended the ED/ER following
trauma or complaining of pain.
See if you can identify the injury or problem
revealed in each radiograph.
Beware. Some of the radiographs may be
normal.
Answers are on p. 380.
Test Yourself—answers
1. Galeazzi fracture dislocation, p. 146.
2. Stress (fatigue) fracture 3rd metatarsal, p. 299.
3. Normal. The widened space on the left side of the peg
and the asymmetric alignment of the lateral masses on
the right side are due to positional rotation of the neck,
p. 182.
4. Isolated blow out fracture of the left orbit with a
teardrop and haemorrhage (fluid level) in the maxillary
antrum, pp. 64–67.
5. Apical oblique view of the shoulder, p. 76; posterior
dislocation of the head of the humerus, p. 89.
6. Odontoid peg fracture, p. 188.
7. Apical oblique view of the shoulder; p. 76. (1) Anterior
dislocation of the head of the humerus, p. 84. (2)
Detached fragment medial to the head; (3) Hill–Sach's
lesion, p. 85.
8. Bennett's fracture—dislocation of the thumb, p. 165.
9. Undisplaced fracture of the distal radius, p. 136.
10. Fat-fluid level in the suprapatellar bursa, p. 249; an intraarticular fracture is not evident on this single view, but is
presumed to be present.
11. Supracondylar fracture with minimal posterior
displacement, pp. 106–108.
12. Dislocations at the 4th and 5th carpometacarpal joints,
pp. 156–157, 168.
13. Greenstick fracture of the distal radius, pp. 18–19.
14. Normal OM radiograph, pp. 55, 60–61.
15. Avulsion of the apophysis of the right anterior inferior
iliac spine (AIIS), pp. 223, 236–237.
16. Fractures of the C6 and C7 spinous processes, pp. 192.
17. Fracture of the lateral tibial plateau, pp. 250–253.
18. Central dislocation/displacement of the right femoral
head. Acetabular fracture, pp. 219, 240.
19. The important finding: fracture through the neck of the
talus, p. 282.
20. Normal Lisfranc joints and normal tarsal bones, pp. 294–
297, 303.
21. Normal apophysis at the base of 5th metatarsal, p. 298;
multicentric ossification is also normal, p. 305.
22. Dislocated head of the radius, pp. 104, 112.
23. Subluxation at the acromioclavicular joint. Also, suspect
a tear of the coracoclavicular ligaments, pp. 86–87.
24. Fracture involving the volar plate, and a mallet finger
fracture, pp. 154, 159, 161.
25. Fracture of the calcaneum: abnormal Bohler's angle, pp.
277–279.
26. Segond fracture, p. 259.
27. Forward subluxation of C4 on C5 vertebra, p. 193; (2)
fracture of the odontoid peg, pp. 188–189.
28. Lisfranc-subluxation at the base of the 2nd metatarsal,
pp. 295–297, 302–303.
23 Glossary
Further reading: Lee P, Hunter TB, Taljanovic M.
Musculoskeletal Colloquialisms: How Did We Come
Up with These Names? Radiographics
2004;24:1009–1027.
Accident and Emergency Department. See: Emergency
Department.
AP. Antero-posterior. Indicates direction of X-ray beam
passing through the patient.
Axial radiograph aka axial projection or axial view. The Xray beam is directed along a plane parallel to the long
axis of the body. Example: axial view of calcaneum.
AXR (UK) aka KUB (USA). An abdominal radiograph.
Basal joint of the thumb. The 1st carpometacarpal joint
(ie trapezium-metacarpal joint).
Baseball finger (USA). See: Mallet finger (UK) Battered
baby syndrome. See: Non-accidental injury (NAI).
Bayonet apposition. Describes the relationship of two
fracture fragments when they lie next to, or adjacent to,
each other rather than in end-to-end contact.
Bone bruise. Focal oedema and haemorrhage secondary
to microfractures of the trabeculae. Can only be
demonstrated by MRI. May take up to 4 months to heal.
Bowing fracture. See: Plastic bowing fracture.
Buddy strapping. See: Garter strapping.
Button battery aka Disc battery. Battery often used in
watches and calculators.
Calcaneum aka Calcaneus.
Capitellum aka Capitulum.
Carpal navicular (USA) aka Scaphoid bone (UK) Coffee
bean shadow aka the reversed D shadow. A Survival
Guide analogy/contrivance used to describe the anterior
arch of the C1 vertebra as it appears on the lateral view
of the cervical spine. This shadow is readily visible on all
lateral radiographs and very approximately resembles a
coffee bean. The analogy has been coined in order to
assist the inexperienced doctor to identify and focus on
this specific landmark shadow when analysing the
anatomy at the C1/C2 articulation.
Compartment Syndrome. Fascial tissue surrounds and
separates groups of muscles in the arms and legs. Within
each fascial layer there is a confined space, termed a
compartment. Swelling within a fascial compartment (ie
oedema or blood) can compress the contained muscles,
nerves, and blood vessels. Rising pressure can obstruct
the blood flow to the compartment and cause permanent
injury to the muscle and nerves. Consequently there can
be extensive or complete replacement of the muscle by
scar tissue.
CTR. Cardiothoracic ratio. A measurement. Indicates
whether the heart is likely to be enlarged.
Decubitus position. Patient is reclining. Denotes that the
patient is lying on his or her side. Implies that a
horizontal beam radiograph has been obtained. A
technique which can be used to demonstrate free intraabdominal air or to confirm fluid in the pleural space.
Diaphysis. The shaft of a long bone. It merges with the
metaphysis at either end. See: Epiphysis, Metaphysis,
Physis.
Diastasis. Separation of normally adjacent bones with or
without an associated fracture, or a separation at a site
of fibro-cartilaginous union. Examples: the tibia and
fibula at the ankle mortice; a sacroiliac joint; a skull
suture.
Dorsal. Relating to the posterior (extensor) aspect of the
body or of a body part (eg a limb). See: Ventral.
Emergency Department or ED (UK) aka Emergency
Room or ER (USA), Accident Department (UK); Accident
and Emergency Department (UK); Casualty (UK).
Epiphyseal fusion aka Epiphyseal closure. The epiphysis
when fully ossified merges with the metaphysis of the
long bone. The age at which ossification and fusion
occurs varies from bone to bone. There is a slight
variation in the age at which fusions occur in males and
females.
Epiphysis. The epiphysis forms the bone-end. It enlarges
by growth of cartilage within the secondary centre
adjacent to the growth plate. Gradually the epiphysis
ossifies, and it eventually fuses to the metaphysis when
the growth plate disappears. See: Epiphyseal fusion;
Metaphysis.
Fluoroscopy (USA, UK) aka Screening (UK); Fluoroscopic
screening. Viewing an area of anatomy on a screen or on
a monitor utilising a machine which provides a real time
X-ray image. Can (for example) be used to detect air
trapping in a child who may have aspirated a foreign
body. Also used to assist in the manipulation of fractures.
Garter strapping aka Buddy strapping. A method of
immobilising some phalangeal fractures. The injured
digit is strapped to an adjacent uninjured digit.
Growth plate aka Cartilaginous growth plate, Epiphyseal
plate, Epiphyseal disc. The layer of cartilage between the
metaphysis and epiphysis of an unfused long bone.
Sometimes referred to as the Physis.
GSW. Gun shot wound.
Hip pointers. Contusions to the iliac crest causing pain,
localized tenderness, and discomfort when weight
bearing.
Horizontal beam radiograph aka Cross table radiograph.
Denotes the orientation of the X-ray beam relative to the
floor. The beam is parallel to the floor. This technique
may be used to demonstrate a fluid level (eg in the
suprapatellar bursa of the knee), or utilised when a
patient should not be moved from the supine position (eg
lateral cervical spine radiograph following trauma).
Insufficiency fracture. A fracture occurring as the result
of a normal stress on an abnormal bone (eg a vertebral
fracture occurring without trauma or a fall in an elderly
patient who has osteoporosis). Aetiologically completely
different from a stress fracture.
Intravenous urogram (IVU) aka Excretory urogram,
Intravenous pyelogram (IVP).
Isotope investigation aka Nuclear medicine investigation,
Radio-isotope study, Radionuclide scan, Scintiscan,
Scintigraphy.
KUB (USA) aka AXR (UK). An abdominal radiograph.
Light of day appearance. The normal appearance of the
4th and 5th carpometacarpal joints on all posterioranterior radiographs of the hand. It has a specific
relevance to a patient who presents with a hand injury
after punching a wall. Loss of the light of day appearance
raises the strong probability of a dislocation of the
affected carpometacarpal joint.
Lipohaemarthrosis. Liquid fat and blood within a joint
demonstrable on a horizontal beam radiograph. Most
commonly seen at the knee joint when marrow fat enters
the joint via an intra-articular fracture and forms a fatfluid level (FFL). Occasionally referred to as a fat-blood
interface or FBI.
Lisfranc joints. The tarsometatarsal joints. Usually
referred to in the context of a Lisfranc fracture
dislocation; the most common dislocation or subluxation
of the foot.
Lucent. Denotes a dark line, or dark area, on a radiograph.
Commonly used as a descriptive term to indicate that a
fracture is identifiable by a lucent line (or lucency).
Lytic. The opposite of sclerotic. Denotes an area on a bone
radiograph which appears darker or blacker than the
adjacent normal bone. The word lytic often implies bone
destruction. Sometimes used as a synonym for lucent.
Mallet finger (UK) aka Baseball finger (USA). A flexion
deformity of a distal interphalangeal joint with or without
a fracture of the dorsum at the base of the terminal
phalanx. The injury represents an avulsion of the
extensor tendon.
March fracture aka Fatigue fracture, Stress fracture. It is
common for the term March fracture to be used in
reference (specifically) to a stress fracture of a
metatarsal. A recognized complication during the
training period for recruits into the army.
Metaphysis. The region of bone between the growth plate
and the shaft (diaphysis) of a long bone.
MRI aka MR. Magnetic resonance imaging.
MVA (USA) aka Motor vehicle accident (USA), Road traffic
accident or RTA (UK).
Non-accidental injury (NAI) aka Battered baby, Battered
child, Child abuse. Euphemism for a deliberate assault
and injury to a young child or infant.
Nursemaid's elbow (USA) aka Pulled elbow (UK).
Occipitomental radiograph of the face (OM) aka
Water's projection. Radiograph of facial bones obtained
with the axis of the X-ray beam directed between chin
and occiput. A following number (eg OM30 or OM15)
denotes the degree of angulation of the X-ray beam.
Odontoid peg aka the dens, or the peg of the axis (C2)
vertebra.
Oedema (UK) aka Edema (USA).
OPG aka Orthopantomogram, OPT, Panoramic view. A
tomographic device specifically designed to demonstrate
the mandible and part of the maxilla.
Ossification. The process by which bone is formed. Most
commonly bone forms from cartilage (eg a long bone).
Less commonly bone forms from membrane (eg skull).
Ossification can also occur in the soft tissues either as
the result of haemorrhage following trauma or due to
chronic inflammation.
Osteochondral fracture. Fracture involving a joint
surface and the fracture fragment consists of a small
piece of bone and cartilage. The cartilaginous component
is invisible on the plain radiograph. Example:
osteochondral fracture of the dome of the talus.
PA. Postero-anterior. Indicates the direction of the X-ray
beam passing through the patient.
Paediatrics (UK) Pediatrics (USA).
Palmar. Relating to the palm of the hand (ie the ventral
surface).
Periosteal new bone formation aka Periosteal reaction,
subperiosteal new bone formation. Appearance of a thin
white line along part of the shaft of a long bone which
appears to be separated from the cortex by a small
space. The periosteum is invisible on a radiograph, and
the reaction (or new bone) is a layer of ossification deep
to the invisible periosteum. The small space between the
white line and the bone is due to elevation of the
periosteum by blood, pus, or tumour. In the context of
trauma a periosteal reaction is a normal healing
response.
Physis. See Growth plate.
Plastic bowing fracture aka Plastic deformity, Bowing
fracture. A type of long bone fracture occuring in
children. The force is predominantly that of a
longitudinal stress on an immature long bone. A series of
microfractures occur, causing the bone to bend, adopting
a smooth curve, with no obvious abnormality of the
cortex. Most commonly occurring in the forearm bones;
may also affect the tibia, the fibula, and the clavicle.
Radiographer (UK) aka Radiographic technician (USA) or
Radiologic technologist (USA).
Radionuclide investigation. See: Isotope investigation.
Renal colic aka Ureteral colic, Ureteric colic.
RTA aka Road traffic accident (UK), Motor vehicle accident
or MVA (USA).
Scaphoid bone (UK) aka Carpal navicular (USA).
Scintigraphy. See: Isotope investigation.
Sclerotic. Denotes a dense (white) line or area on a
radiograph. May be at the periphery or cortex of a bone
(eg the sclerotic appearance of maturing callus
surrounding a healing fracture), or traversing the shaft
of a bone (eg impacted fracture).
Screening (UK) aka Fluoroscopy (UK, USA). Fluoroscopic
screening. See: Fluoroscopy.
Skyline view aka Sunrise or Sunset view. A tangential
radiograph of the knee which provides a supero-inferior
view of the patella and of the patellofemoral joint.
Stress fracture aka Fatigue fracture, March fracture. A
fracture resulting from minor but repeated injury to an
otherwise normal and healthy bone.
Subluxation. The articular surfaces of adjacent bones
maintain some contact; ie the joint surfaces are no longer
congruous but contact has not been completely
disrupted.
Sudeck's atrophy aka Reflex sympathetic dystrophy
syndrome. Chronic persistent pain associated with severe
localised reduction in bone density. Most commonly
occurs as a result of trauma with or without a fracture.
Swimmer's view. A lateral projection used to show the
cervicothoracic junction. The name derives from the
patient's position (one arm fully extended, the other by
the side), which simulates that of a swimmer doing either
the back stroke or the crawl (freestyle).
Symphysis. A joint between adjacent bones lined by
hyaline cartilage and stabilised by fibrocartilage and
ligaments. Example: symphysis pubis.
Synchondrosis. The site of a persistent plate of cartilage
between adjacent bones, at which little or no movement
occurs. Example: zygomaticofrontal synchondrosis.
Technician (USA) aka Radiographer (UK), Radiographic
Technician (USA), Radiologic Technologist (USA).
Tibial plafond. The distal articular surface of the tibia.
Trapezium bone (UK) aka Greater multangular (USA).
Trapezoid bone (UK) aka Lesser multangular (USA).
Triquetral bone aka Triquetrum.
Tuberosity. Any prominence on a bone to which a tendon
or tendons are attached (eg tuberosity at the base of the
fifth metatarsal).
Two Bone Rule. See description on page 146.
Valgus. An angular deformity at a joint or fracture site in
which the distal bone (or bone fragment) is deviated
away from the midline.
Varus. An angular deformity at a joint or fracture site in
which the deviation of the distal bone (or bone fragment)
is towards the midline.
Ventral. Relating to the anterior (flexor) aspect of the body
or body part (eg a limb). See: Dorsal.
Vertical beam radiograph. Denotes the orientation of the
X-ray beam with respect to the floor. The beam is at right
angles to the floor.
View. aka Projection, Position, or Method. In the context of
diagnostic radiology this refers to the position of the
patient, or of the X-ray tube, when a radiographic
exposure occurs. Examples: frontal view, lateral view.
Volar. Relating to the palm of the hand or the sole of the
foot.
Well corticated. A term used to describe the appearance
of the periphery of a bone (eg an accessory ossicle)
where it is seen to have a dense smooth margin. This
appearance contrasts with the incompletely corticated
margin of a fracture fragment
Index
Abdomen, 329–342
abdominal pain, 334
aorta, aneurysm, 331, 340
aorta, rupture, 340
AXR, usefulness, 330–331
biliary disease, 340
blunt trauma, 341
checklists, 332–333
common problems, 334–340
constipation, 337
FAST scanning, 341
first line investigation, choosing, 329
foreign body ingestion, 349–362
intestinal obstruction, 330, 331, 336–337
penetrating injury, 341
perforation, 331, 335
radiographs, standard, 330, 334–335
renal colic, 331, 338–339
Accessory ossicles
ankle, 288, 291
foot, 292, 304
knee, 262
shoulder, 93
Accessory skull sutures, 40–45
Acetabulum, fractures, 219, 238, 239, 240
Acromioclavicular joint, 75, 86–87
American synonyms, 373–376
Ankle and hindfoot, 265–292
accessory ossicles, 288, 291
anatomy, 266–269
Bohler's angle, 266, 272, 278
checklists, 270–273
common injuries, 274–281
dislocations, 289
fracture, calcaneum, 277–279, 288
fracture, distal tibia, 285
fracture, 5th metatarsal, 276
fracture, Maisonneuve, 284
fracture, malleoli, 274–275
fracture, talus, 282
fracture, Tillaux, 287
fracture, triplane, 286
ligamentous injuries, 274, 281
ligaments, 267, 274
Maisonneuve fracture, 284
mortice joint, 268, 270–271
osteochondral lesions, 283
os trigonum, 288, 292
radiographs, standard, 265
Salter–Harris fractures, 280, 286–287
syndesmotic widening, 270, 281
Aorta, 326
dissection, 326
traumatic rupture, 326
Apophysis, definition, 26
avulsion, 26–27, 222–223, 236–237
Attenuation of X-ray beam, 2
Avulsion injuries, 26–27, 222–223, 236–237, 276, 298
Bankart's lesion, 85
Barton Fracture, 138
Baseball Finger, 161
Battered baby, 31–33, 35–46
Bennett's fracture—dislocation, 153, 165
Bezoars, 361
Black Eyebrow Sign, 66–67
Blow out fracture, 64–67
Bohler's angle, 266, 272, 278
Bowing fracture, 20–21, 112–113
Boxer's fracture, 163
Bucket handle fracture, 33
Bumper fracture, 247, 250–253
Button Battery, swallowed, 358
Calcaneal fractures, 277–279, 288
Car bumper fracture, 247, 250–253
Cardiothoracic ratio, 309, 321
Carpal navicular, bone, 134–135, 144
Carpometacarpal joints
anatomy, 156–157
dislocation, 167–168
Cervical spine, 171–198
anatomy, 172–173
checklists, 174–185
coffee bean appearance, 174–175
common injuries, 186–193
contour lines, 176, 178, 194, 197
radiographs, standard, 2–3
delayed instability, 196
dens identification, 175
developmental variants, 173, 195
fracture, hangman's, 186
fracture, Jefferson, 187
fracture, odontoid peg, 188–189
fracture, vertebral body, 192
Harris' ring, 176–177, 188
lining up the lateral masses, 180, 186–187, 191
mach effect, 183
pitfalls, 195–197
polomint, lifesaver and the C1 vertebra, 186
prevertebral soft tissues, 179
transverse ligament, 181, 186–187, 191
unilateral facet dislocation, 194
vertebral body, asymmetric development, 182
Checklists
abdomen, 332–333
ankle and hindfoot, 270–273
cervical spine, 174–185
chest, 312–315
elbow, adult, 118–120
elbow, paediatric, 102–105
face, 58–61
hand, 158–159
hip and proximal femur, 230–231
knee, 246–249
lumbar spine, 202–205
midfoot and forefoot, 296–297
pelvis, 216–217
penetrating foreign body, 346–348
shoulder, 78–79
skull, adult, 50–51
skull, in suspected NAI, 40
thoracic spine, 202–205
wrist, 128, 132
Chest
anatomy, 308–311
aortic dissection, 326
aortic rupture, 326
asthmatic attack, 323
cardiac enlargement, 309
checklists, 312–315
heart failure, 321–322
hilum, 309
inhaled foreign body, 30
lateral radiograph, 310–311, 314–315
left ventricular failure, 321–322
mediastinal fat, 318
pain, 327
pleural effusion, 324–325
pneumomediastinum, 323
pneumonia, 316–318
pneumothorax, 319–320
pulmonary embolus, 327
pulmonary venous hypertension, 321–322
radiographs, standard, 307
rib fracture, 327
septal lines, 322
silhouette sign, 316
ten clinical problems, 316–328
tricky, hidden, areas, 308
Chicken bones, swallowed, 350, 354
Children
bones, 11–34
bones, different to adults, 12
chest emergencies, 30
child abuse, 31–33
elbow injury, 95–114
growth plate (physis), 12
particular paediatric points, 11–34
periosteum, normal, 12
plastic bowing fracture, 21, 112–113
skull, accessory sutures, 40–45
skull injury, 35–46
sports injuries, 24–29
Clavicle, fracture, 81
Coffee bean shadow, 174–175
Coins, swallowed, 350–351
Compass, use of, 350
Coracoclavicular ligament injury, 75, 86, 87
Corner fracture, 32
CRITOL sequence, 98–100
Dental appliances, swallowed, 360
Dislocations
Bennett's fracture—dislocation, 153, 165
carpometacarpal joints, 167–168
Galeazzi injury, 146
head of femur, 239–241
head of humerus, 82–85
head of radius, 101, 104, 112–113, 120, 123
Lisfranc, 295–297, 302–303, 306
lunate and perilunate, 130, 148–150
Monteggia injury, 104, 112–113, 123
shoulder, 82–85
tarsometatarsal joints, 302–303
Elbow, adult, 115–124
anatomy, 116–117
checklists, 118–120
common injuries, 121
cystic lucency, radius, 124
fat pads, 115, 117, 118–119
fracture, head of radius, 119, 121
fracture, olecranon, 122
Monteggia injury, 123, 146
radial tuberosity, pitfall, 124
radiocapitellar line, 117, 120
radiographs, standard, 115
supracondylar spur, 124
Elbow, paediatric, 95–114
anatomy, 96–97
anterior humeral line, 101, 103
checklists, 102–105
common injuries, 106–111
CRITOL sequence, 98–100
dislocation, head of radius, 112
fat pad displacement, 95, 97, 102, 115, 117–119
fracture, supracondylar, 106–108
medial epicondyle, 26, 100, 105
Monteggia injury, 104, 112–113, 146
nursemaid's, 111
ossification centres, 98–100
plastic bowing, 20–21, 112–113
pulled, 111
radiocapitellar line, 101, 104, 114
radiographs, standard, 95
Elephant's trunk, 60
Epiphyseal fractures, 14–17, 286, 287
Epiphysis, 13–14
Face
anatomy, 54–57
checklists, 58–61
common injuries, 62–67
four legged stool, 58–61
fracture, blow out, 64–67
fracture, mandible, 68–72
fracture, tripod, 63
nasal injury, 53
OM views, 53, 55
OPG radiograph, 56–57, 68–70
radiographs, standard, 53, 55
zygomatic bone, 54–55, 58–67
FAST scanning, 341
Fat-fluid level (knee), 249
Fatigue fracture, 24, 229, 301
Fat pad displacement (elbow), 95, 97, 102
Femoral neck fracture, 232–234
Fender fracture, 247, 250–253
Fibula, neck fracture, 256
Fighter's fracture, 163
Fingers, 153–170
anatomy, 154–157
checklist, 158–159
common injuries, 160–163
radiographs, standard, 153
Fish bones, swallowed, 352–354
Foot. See Forefoot; Hindfoot; Midfoot
Forefoot. See (Midfoot and forefoot)
Foreign bodies, 343–348, 349–362
bezoar, 361
button battery, swallowed, 358
chicken bones, swallowed, 350, 354
coins, swallowed, 350–351
compass, use of, 350
dentures, swallowed, 360
fish bones, swallowed, 352–354
glass injury, 344, 346
gun shot wound, 345, 346
inhaled, 30
large objects, swallowed, 360–361
magnets, swallowed, 359
metal detector scanning, 350
orbital, 347–348
penetrating, 343–348
sharp, swallowed, 349–362
swallowed, 349–362
ultrasound scanning, 346, 347
wood or plastic, penetrating, 344–345
Fractures (see individual skeletal sites)
angulation, 8
avulsion, 26–27, 222–223, 236–237, 276, 298
description, essential features, 6–8
displacement, 8
greenstick, 18
Jones, 301
plastic bowing, 21
Salter–Harris, 15–17, 280, 281, 286–287
spiral, 7, 153, 162
stress, 24, 229, 301
Tillaux, 287
toddler's, 22–23
torus, 18
triplane, 286
Galeazzi fracture, 146
Gamekeeper's thumb, 166
Glass foreign bodies, 344, 346
Glossary, 373–376
Greenstick fracture, 19
Growth plate (physis), 14–17
fracture, 14–17, 280, 281, 286–287
Hand and fingers, 153–170
abductor pollicis longus, 164–166
accessory epiphyses, 170
anatomy, 154–157
Bennett's fracture dislocation, 153, 165
boxer's fracture, 163
checklists, 158–159
common injuries, 160–163
dislocations, carpometacarpal, 167–168
gamekeeper's thumb, 166
Light of day appearance, 157–158
radiographs, standard, 153
Rolando fracture, 165
sesamoid bones, 169
skier's thumb, 166
spiral fracture, 153
thumb, basal joint, 155, 164–165, 169
Harris' Ring, 176–177, 188
Head injury
adults, 47–52
infants and small children, 35–46
non accidental injury, 35–46
Heart failure, 321–322
size, 309
Hill Sachs' deformity, 85
Hindfoot. See (ankle and hindfoot)
Hip and proximal femur, 227–242
anatomy, 228
apophyseal injury, 222–225, 236–237
apophyses, 229
checklists, 230
common injuries, 232–235
dislocations, 239–241
fracture, acetabulum, 238, 239, 240
fracture, femoral neck, 232–234
fracture, pubic ramus, 235
os acetabuli, 226, 242
radiographs, standard, 227–228
Hip pain in children, 230
Inhaled foreign body, 30
Interosseous membrane, lower leg, 270, 281
Intestinal obstruction, 331, 336–337
Intravenous urogram, 338, 340
Jones' fracture, 301
Key Principles, 1–10
Knee, 243–264
anatomy, 244–245, 246–247, 248, 258
avulsed bone fragment, 258–259
checklists, 246–249
common injuries, 250–259
cruciate ligament injury, 251, 259
effusion, 249
fat-fluid level, 249
fracture, fibula, 256
fracture, patella, 254–255
fracture, plateau, 247, 250–253
fracture, tibial spine, 257
fragments around the knee, 258–259
ligaments, 244–245, 251, 258
lipohaemarthrosis, 249
Osgood Schlatter's disease, 263
osteochondral lesion, 255
Osteochondritis dissecans, 28–29, 257
patella dislocation, 260
patellar tendon rupture, 245, 261
Pellegrini–Stieda lesion, 262
pitfalls, 262–263
radiographs, standard, 243
Segond fracture, 259
suprapatellar strip, 245, 248
Large bowel obstruction, 331, 336–337
Light of day appearance, 157–158, 167–168
Lipohaemarthrosis, 249
Lisfranc injury, 295–297, 302–303, 306
Little Leaguer's elbow, 110
Lumbar spine, 199–212
anatomy, 200–201
checklists, 202–205
common injuries, 206
fracture, burst, 207, 209
fracture dislocation, 208, 209
fracture, flexion compression (wedge), 207, 209
fracture, flexion distraction (Chance), 208, 209
fracture, pathological, 210–211
fracture, transverse process, 209, 211
instability, 209
radiographs, standard, 199
Schmorl's nodes, 212
three column principle, 200, 209
Lunate dislocation, 148–150
Lung consolidation, 316–318
Mach effect, 183
Madonna sign, 147
Magnets, swallowed, 359
Maisonneuve fracture, 284
Mallet finger, 161
Mandible, 56–57, 68–70
anatomy, 56–57
artefacts, 69, 71
fractures, 68–72
OPG view, 56–57, 68–70
PA radiograph, value of, 68
radiographs, standard, 53
temporomandibular joint, 57–58
March fracture. See (Stress fracture)
Mendosal suture, 36–37, 41–43
Metal detector scanning, 350, 356, 359
Metatarsals, 294–299
dislocations, 302–303
fifth, fracture of base, 276, 298
stress fractures, 24, 25, 299, 301
Midfoot and forefoot, 293–306
accessory ossicles, 304
anatomy, 293
apophysis, 298, 305
checklists, 296–297
cleft epiphysis, 305
common injuries, 298–299
cuneiform mortice, 295
dislocations, tarsometatarsal, 302–303
fatigue fracture. See (stress fracture)
fracture, base of 5th metatarsal, 298
fracture, Jones, 301
fracture, metatarsals, 300–301
fracture, tarsal bones, 300
Freiberg's infraction, 306
Lisfranc joint, 295–297, 302–303, 306
os intermetatarseum, 304
radiographs, standard, 293
sesamoid bones, 304
stress fractures, 24, 25, 299, 301
Monteggia injury, 104, 112–113, 123, 146
Nasal bone, 53
Nightstick injury, 143
Non-accidental injury (NAI), 31–33, 35–46
Nursemaid's elbow, 111
Odontoid peg, 172–177, 180–183
Orbit, 58–63
foreign body in, 348
fracture, blow out, 64–67
fracture, inferior margin, 64
fracture, tripod, 58–63
Orthopantomogram (OPG), 56–57, 68–71
Os Intermetatarseum, 304
Osteochondral fracture, 28–29, 255, 257, 283
Paediatric radiology, 11–34, 35–46
Paraspinal line, 201, 204, 206, 210–211
Particular Paediatric Points, 11–34
Patella, 244–246, 248–249, 254–255
fracture, 254–255
tendon rupture, 261
Pelvis, 213–226
acetabular impingement injury, 226
anatomy, 214–215, 217
apophyses, 215, 217, 222–223, 236–237
checklists, 216–217
common injuries, 222
fracture, acetabulum, 219, 238, 239, 240
fractures, avulsion, 222–225, 236–237
fracture, coccygeal, 222
fractures, high energy trauma, 218–221
fractures involving a bone ring, 218–219
fractures,low energy trauma, 222–223
fracture, sacrum, 220–221
os acetabuli, 226, 242
radiographs, standard, 213
sports injuries, 224–225
synchondroses, 214
Penetrating foreign bodies, 343–348
Perforation, bowel, 335, 357, 359, 361
Perilunate dislocation, 148–150
Periosteal new bone, 22–23, 299
Periosteum, 12, 18–19
Plastic bowing fracture, 20–21, 112–113
Pleural effusion, 324–325
encysted, 324
on supine radiograph, 325
subpulmonary, 324
Pneumonia, concealed, 316–318
Pneumothorax, 5, 319–320
Proximal femur, 227–242
injuries, 232–239
radiographs, standard, 227
Pulled elbow, 111
Pulmonary oedema, 321–322
Radius
cystic lucency, pitfall, 124
dislocation, of the head, 101, 104, 112–113, 120, 123
fracture, 12, 16, 18–21, 136–141
Renal colic, 338–340
Reverse Barton fracture, 138
Rib fracture, 327
Rolando fracture, 165
Rules to apply, when assessing a radiograph, 5
Sacrum, fracture, 216–217, 220–221
Salter–Harris fracture, 15–17, 280, 281, 286–287
Satisfaction of search phenomenon, 5
Scaphoid fracture, 132–133
Schmorls nodes, 212
Scrapper's fracture, 163
Segond fracture, 259
Sentinel sign, transverse process fractures, 205, 211
Sharp objects, swallowed, 352–357
Shoulder, 73–94
acromioclavicular (AC) joint, 75, 86–87
anatomy, 75–77, 86
anterior dislocation, 82–85
apical oblique view, 76, 79
AP view, 75, 78
axial (armpit) view, 74
Bankart's lesion, 85
checklists, 78–79
common injuries, 80–85, 91
coracoclavicular ligament injury, 75, 86, 87
dislocations, 82–85
fracture, clavicle, 81
fracture, neck of humerus, 90
fracture, scapula, 91
Hill–Sachs' deformity, 85
ossification centres, 93
positioning pitfall, 92–94
posterior dislocation, 88–89
pseudosubluxation, 83
radiographs, the options, 74–77
rhomboid fossa, 94
walking stick and light bulb appearances, 88
Y (lateral scapular) view, 77
Skier's thumb, 166
Skull, adult, 47–52
anatomy, 48–49
imaging examination of choice, 47
recognising a fracture, 50
sphenoid sinus fluid level, 51
Skull, infants and toddlers, 35–46
accessory sutures, 40–45
anatomy, 36–39, 41–45
basic radiographs, 45
non-accidental injury, 31, 32, 35–46
Small bowel, 330–331
obstruction, 336–337
Sphenoid sinus, fluid level in, 50–51
Sports injuries, 24–29, 224–225
Stress fracture, 24, 229, 301
calcaneum, 24
Jones, 301
lumbar spine, 24
metatarsals, 24, 25, 299, 301
sports injuries, causing, 24
tibia, 24, 25
Subluxation, definition, 9
Swallowed foreign bodies, 349–362
Synonyms USA: UK, 373–376
Talus, fractures, 282–283
Tarso–metatarsal joints, 294–297, 302–303
Terry Thomas sign, 147
Test Yourself cases, 363–373
Thoracic spine, 199–212
anatomy, 200–201
checklists, 202–205
common injuries, 206
instability, 209
paravertebral stripe, 201, 204, 206, 211
pathological fracture, 210–211
radiographs, standard, 199
Schmorl's nodes, 212
three column principle, 200, 209
Thumb, 154–155
anatomy, 154, 155
basal joint, 154, 164–165
dislocations, 165
fractures, 164–165
ligaments, 155
mobility, extreme, 155
Tibia, 244–247, 250–253
plateau fracture, 250–253
spiral fracture, 22–23
stress fracture, 24, 25
Toddler's fracture, 22–23
Torus fracture, 18–19
Towne's view, 48
Tripod fracture, 58–63
four legged stool concept, 58–61
Triquetral fracture, 145
Two bone rule, 123, 146
Ulna, distal radio-ulna joint, 128–129
Galeazzi injury, 146
night stick injury, 143
styloid fracture, 142
two bone rule, 146
Ureteric colic, 338–340
USA synonyms, 373–376
Volar plate injury, 154, 161
Wood splinters, 344–345
Wormian bones, 44
Wrist, 125–152
accessory ossicles, 152
anatomy, 126–127
checklists, 128, 132
common fractures, 136–143
fracture, Barton, 138
fracture, Galeazzi, 146
fracture, hamate, 148
fracture, scaphoid, 134–135, 144
fracture, triquetral, 145
lunate dislocation, 148–150
Madonna sign, 147
nightstick injury, 143
perilunate dislocation, 148–150
radial beak, pitfall, 151
radiographs, standard, 125, 132–133
radio–ulnar joint, dislocation, 128–129
scaphoid series, 132–133
scapholunate separation, 147
X–ray beam (key principles), 2–3
effect on radiograph, 2
patient position, 5
Zygomatic arch, 54–63
anatomy, 54, 58–60
elephant's trunk appearance, 60
fractures, 62–63
leg 1 of the four legged stool, 58–60
tripod fracture, 58–63